Both privilege escalation vulnerabilities stem from bugs in the kernel’s handling of page caches stored in memory, allowing untrusted users to modify them. They target caches in networking and memory-fragment handling components. Specifically, CVE-2026-43284 attacks the esp4 and esp6 () processes, and CVE-2026-43500 zeroes in on rxrpc. Last week’s CopyFail exploited faulty page caching in the authencesn AEAD template process, which is used for IPsec extended sequence numbers. A 2022 vulnerability named Dirty Pipe also stemmed from flaws that allow attackers to overwrite page caches.

Researchers from security firm Automox wrote:

Dirty Frag belongs to the same bug family as Dirty Pipe and Copy Fail, but it targets the frag member of the kernel’s struct sk_buff rather than pipe_buffer. The exploit uses splice() to plant a reference to a read-only page-cache page (for example, /etc/passwd or /usr/bin/su) into the frag slot of a sender-side skb. Receiver-side kernel code then performs in-place cryptographic operations on that frag, modifying the page cache in RAM. Every subsequent read of the file sees the corrupted version, even though the attacker only ever had read access.

CVE-2026-43284 is found in the esp_input() process on the IPsec ESP receive path. When an skb object is non-linear but lacks a frag list, the code skips skb_cow_data() and decrypts AEAD in place on the planted frag. From there, an attacker can control the file offset and the 4-byte value of each store.

CVE-2026-43500, meanwhile, resides in rxkad_verify_packet_1(). The process decrypts RxRPC payloads using a single-block process. Splice-pinned pages become both a source and destination. That, paired with the decryption key being freely extracted using the add_key (rxrpc), allows an attacker to rewrite contents in memory.

Either exploit used separately is unreliable. Some Ubuntu configurations use AppArmor to prevent untrusted users from creating namespace contents. That, in turn, neutralizes the ESP technique. Most other distributions by default don’t run rxrpc.ko, which neutralizes the RxRPC arm. When chained together, however, the two exploits allow attackers to obtain root on every major distribution Kim tested. Once the exploits run, attackers can use SSH access, web-shell execution, container escapes, or compromise low-privilege accounts.

“Dirty Frag is notable because it introduces multiple kernel attack paths involving rxrpc and esp/xfrm networking components to improve exploitation reliability,” Microsoft researchers wrote. “Rather than relying on narrow timing windows or unstable corruption conditions often associated with Linux local privilege escalation exploits, Dirty Frag appears designed to increase consistency across vulnerable environments.”

Researchers at Google-owned Wiz said exploits will be less likely to break out of hardened containerized environments such as Kubernets with default security settings in place. “However, the risk remains significant for virtual machines or less restricted environments.”

The best response for anyone using Linux is to install patches immediately. While fixes likely require a reboot, protection from a threat as severe as Dirty Frag outweighs the cost of disruptions. Anyone who can’t install immediately should follow the mitigation steps laid out in the posts linked above. Additional guidance can be found here.

https://arstechnica.com/security/2026/05/linux-bitten-by-second-severe-vulnerability-in-as-many-weeks/

Chaos erupted at schools and colleges throughout the US on Thursday as a cyberattack disrupted online learning platform Canvas just as students were due to take final exams.

Canvas parent company Instructure said that as of Friday morning, the platform was back online. Instructure said it temporarily took Canvas offline on Thursday after identifying unauthorized activity in its network. The threat actor was the same one responsible for a data breach that Instructure disclosed a week ago. Data accessed included user names, email addresses, student ID numbers, and messages exchanged on the platform. The company said it has no indication that passwords, dates of birth, government identifiers, or financial information were involved.

Schools and colleges scramble

A ransomware group known as ShinyHunters claimed responsibility for the breach on its dark web site. It claimed the data it took came from 275 million people associated with 8,800 schools.

As students were trying to prepare for and take final exams Thursday, Canvas login pages displayed a ransom demand. It said Instructure had rebuffed the group’s earlier demands and encouraged individual schools to negotiate directly with them. The note and the outage sent schools and colleges scrambling. The University of Illinois reportedly postponed all final exams and assignments scheduled for Friday, Saturday, and Sunday. The University of Massachusetts Dartmouth rescheduled or extended due dates for exams. The University of California system directed all its campuses to linkword.

Canvas isn’t the only learning platform to be struck by a cyberattack. Last year, PowerSchool, a firm that provides cloud-based software to 60 million students from 16,000 K–12 schools worldwide, disclosed a breach that exposed years’ worth of sensitive data, including names, addresses, and disciplinary records.

ShinyHunters has operated for years as a loose collective. In 2024, it made off with a trove of credentials and other data from cloud storage provider Snowflake and used it in follow-on breaches of Snowflake customers, including TicketMaster.

https://arstechnica.com/security/2026/05/chaos-erupts-as-cyberattack-disrupts-learning-platform-canvas-amid-finals/

Websites for some of the world’s most prestigious universities are serving explicit porn and malicious content after scammers exploited the shoddy record-keeping of the site administrators, a researcher found recently.

The sites included berkeley.edu, columbia.edu, and washu.edu, the official domains for the University of California, Berkeley, Columbia University, and Washington University in St. Louis. Subdomains such as hXXps://causal.stat.berkeley.edu/ymy/video/xxx-porn-girl-and-boy-ej5210.html, hXXps://conversion-dev.svc.cul.columbia[.]edu/brazzers-gym-porn, and hXXps://provost.washu.edu/app/uploads/formidable/6/dmkcsex-10.pdf. All deliver explicit pornography and, in at least one case, a scam site falsely claiming a visitor’s computer is infected and advising the visitor to pay a fee for the non-existent malware to be removed. In all, researcher Alex Shakhov said, hundreds of subdomains for at least 34 universities are being abused. Search results returned by Google list thousands of hijacked pages.

A handful of hijacked columbia.edu subdomains listed by Google

One of the sites redirected by a UC Berkeley subdomain.

Hijacking a university’s good name

Shakhov, founder of SH Consulting, said that the scammers—which a separate researcher has linked to a known group tracked as Hazy Hawk—are seizing on what amounts to a clerical error by site administrators of the affected universities. When they commission a subdomain such as provost.washu.edu, they create a CNAME record, which assignes a subdomain to a “cononical” domain. When the subdomain is eventually decommissioned—something that happens frequently for various reasons—the record is never removed. Scammers like Hazy Hawk then swoop in by hijacking the old record.

With that, they have now hijacked that university’s subdomain. Given the reputations universities have, search queries then flow to the top of Google’s results.

https://arstechnica.com/security/2026/04/why-are-top-university-websites-serving-porn-it-comes-down-to-shoddy-housekeeping/

There is no practical benefit for Kyber developers to have chosen a PQC key-exchange algorithm. The Kyber ransom note gives victims one week to respond. Quantum computers capable of running Shor’s algorithm—the series of mathematical equations that allow the breakage of RSA and ECC (elliptic curve cryptography)—are, at a minimum, three years away and likely much further.

A Kyber variant that targets systems running VMware,  meanwhile, claims to use ML-KEM as well. Rapid7 said its look under the hood revealed that, in fact, it uses RSA with 4096-bit keys, a strength that will take even longer for Shor’s algorithm to break. Anna Širokova, a Rapid7 senior security researcher and the author of Tuesday’s post, said the use or claimed use of ML-KEM is likely just a branding gimmick and that implementing it required relatively little work by Kyber developers.

In an email, Širokova wrote:

First, it’s marketing to the victim. “Post-quantum encryption” sounds a lot scarier than “we used AES,” especially to non-technical decision-makers who might be evaluating whether to pay. It’s a psychological trick. They’re not worried about someone breaking the encryption a decade from now. They want payment within 72 hours.

Second, implementation cost is low. Kyber1024 libraries (renamed to ML-KEM) are available and well-documented. Ransomware doesn’t encrypt your files directly with Kyber1024. That would be slow. Instead, it:

1. Generates a random AES key
2. Encrypts your files with that AES key (fast)
3. Encrypts that AES key with Kyber1024 (so only the attacker can decrypt it)

In Rust, there are already libraries that do Kyber1024. The developer just adds it to their dependencies and calls a function to wrap the key.

Despite the hype, Kyber suggests that PQC is attracting the attention of less technically inclined attorneys and executives deciding how to respond to ransom demands. Kyber developers are hoping the impression that the encryption has overwhelming strength will sway people to pay.

https://arstechnica.com/security/2026/04/now-even-ransomware-is-using-post-quantum-cryptography/

Microsoft released an emergency patch for its ASP.NET Core to fix a high-severity vulnerability that allows unauthenticated attackers to gain SYSTEM privileges on devices that use the Web development framework to run Linux or macOS apps.

The software maker said Tuesday evening that the vulnerability, tracked as CVE-2026-40372, affects versions 10.0.0 through 10.0.6 of the Microsoft.AspNetCore.DataProtection NuGet, a package that’s part of the framework. The critical flaw stems from a faulty verification of cryptographic signatures. It can be exploited to allow unauthenticated attackers to forge authentication payloads during the HMAC validation process, which is used to verify the integrity and authenticity of data exchanged between a client and a server.

Beware: Forged credentials survive patching

During the time users ran a vulnerable version of the package, they were left open to an attack that would allow unauthenticated people to gain sensitive SYSTEM privileges that would allow full compromise of the underlying machine. Even after the vulnerability is patched, devices may still be compromised if authentication credentials created by a threat actor aren’t purged.

“If an attacker used forged payloads to authenticate as a privileged user during the vulnerable window, they may have induced the application to issue legitimately-signed tokens (session refresh, API key, password reset link, etc.) to themselves,” Microsoft said. “Those tokens remain valid after upgrading to 10.0.7 unless the DataProtection key ring is rotated.”

Microsoft describes ASP.NET Core as a “high-performance” web development framework for writing .Net apps that run on Windows, macOS, Linux, and Docker. The open-source package is “designed to allow runtime components, APIs, compilers, and languages [to] evolve quickly, while still providing a stable and supported platform to keep apps running.”

https://arstechnica.com/security/2026/04/microsoft-issues-emergency-update-for-macos-and-linux-asp-net-threat/

Microsoft released an emergency patch for its ASP.NET Core to fix a high-severity vulnerability that allows unauthenticated attackers to gain SYSTEM privileges on devices that use the Web development framework to run Linux or macOS apps.

The software maker said Tuesday evening that the vulnerability, tracked as CVE-2026-40372, affects versions 10.0.0 through 10.0.6 of the Microsoft.AspNetCore.DataProtection NuGet, a package that’s part of the framework. The critical flaw stems from a faulty verification of cryptographic signatures. It can be exploited to allow unauthenticated attackers to forge authentication payloads during the HMAC validation process, which is used to verify the integrity and authenticity of data exchanged between a client and a server.

Beware: Forged credentials survive patching

During the time users ran a vulnerable version of the package, they were left open to an attack that would allow unauthenticated people to gain sensitive SYSTEM privileges that would allow full compromise of the underlying machine. Even after the vulnerability is patched, devices may still be compromised if authentication credentials created by a threat actor aren’t purged.

“If an attacker used forged payloads to authenticate as a privileged user during the vulnerable window, they may have induced the application to issue legitimately-signed tokens (session refresh, API key, password reset link, etc.) to themselves,” Microsoft said. “Those tokens remain valid after upgrading to 10.0.7 unless the DataProtection key ring is rotated.”

Microsoft describes ASP.NET Core as a “high-performance” web development framework for writing .Net apps that run on Windows, macOS, Linux, and Docker. The open-source package is “designed to allow runtime components, APIs, compilers, and languages [to] evolve quickly, while still providing a stable and supported platform to keep apps running.”

https://arstechnica.com/security/2026/04/microsoft-issues-emergency-update-for-macos-and-linux-asp-net-threat/

Grinex, a US-sanctioned cryptocurrency exchange registered in Kyrgyzstan, said it’s halting operations after experiencing a $13 million heist carried out by “western special services” hackers.

Researchers from TRM, which has confirmed the theft, put the value of stolen assets at $15 million after discovering roughly 70 drained addresses, about 16 more than Grinex reported. Neither TRM nor fellow blockchain research firm Elliptic has said how the attackers slipped past Grinex’s defenses. Grinex said it has been under almost constant attack attempts since incorporating 16 months ago. The latest attacks, it said, targeted Russian users of the exchange.

Damaging “Russia’s financial sovereignty”

“The digital footprints and nature of the attack indicate an unprecedented level of resources and technology available exclusively to the structures of unfriendly states,” Grinex said. “According to preliminary data, the attack was coordinated with the aim of causing direct damage to Russia’s financial sovereignty.”

“Due to the attack, the Grinex exchange is forced to suspend operations,” Grinex continued. “All available information has been transferred to law enforcement agencies. An application has been submitted to the location of the infrastructure to initiate a criminal case.”

TRM said that TokenSpot, a second Kyrgyzstan-based exchange, was also breached. Two of the exchange’s addresses sent funds to the same consolidation address used by the affected Grinex-linked wallets. What’s more, both exchanges became inoperable on Wednesday, suggesting they were hit by the same attacker.

TRM said TokenSpot was a front for Grinex, which the US Treasury Department sanctioned last year. The department’s Office of Foreign Assets Control said that Grinex, in turn, was a rebrand of Garantex, an exchange it had sanctioned in 2022. The department said then that Ganantex had “directly facilitated notorious ransomware actors and other cybercriminals by processing over $100 million in transactions linked to illicit activities since 2019.” Last year’s sanctions against Grinex came a few months after TRM said that the exchange was likely a front for Ganantex.

https://arstechnica.com/security/2026/04/russia-friendly-exchange-says-western-special-service-behind-15-million-cyberattack/

Interestingly, Amazon is using SigV4, an impromptu algorithm it developed in-house to make authentication quantum-safe.

“AWS limits the transmission of these secrets to the moment of generation,” Campagna wrote. “Once initially distributed, it is never re-sent to the customer. While we made this decision to operate at the massive scale of AWS, we avoided the need to migrate [to] a public-key based authentication solution.”

For customers who need long-lived roots of trust, Amazon uses its AWS Private CA (certificate authority) with KMS, a key management service that complies with FIPS 204, a NIST certification for post-quantum readiness. Customer data at rest is encrypted and then stored using AES-256, a symmetric algorithm that quantum computers have no advantage over classical computing in breaking.

The most distant PQC readiness deadline is 2033 for Microsoft. Meta and Apple didn’t provide any date at all when asked earlier this week.

“Post-quantum cryptography (PQC) isn’t a flip-the-switch change,” Mark Russinovich, Azure CTO and deputy CISO and technical fellow at Microsoft, wrote in an email. “We have been at the forefront of PQC planning since 2014 as a founding member of the Open Quantum Safe project and a close collaborator with vendors, standards bodies, and government agencies.”

He added that Microsoft’s rollout is guided by three principles: “Prioritize standards—follow NIST, not proprietary crypto; avoid breaking global customers; and roll out in a platform-focused way, starting with Windows, Azure, and identity layers. This mirrors past transitions with SHA and TLS, but with greater urgency given quantum risk.” Note that Russinovich didn’t mention Microsoft’s migration off of MD5.

Meta, meanwhile, hasn’t publicly stated its deadline. On Thursday, the company published a post that mostly rehashed a previous one from two years ago. Neither set a deadline. Instead, Thursday’s post was aimed at advising the industry on key principles. It also introduced a taxonomy of “PQC maturity levels.” They are PQ hardened, PQ ready, PQ aware, and PQ unaware.

https://arstechnica.com/security/2026/04/while-some-big-tech-players-accelerate-pqc-readiness-others-stay-the-course/

Amid customer dissatisfaction around Broadcom’s VMware takeover, rivals have been trying to lure customers from the leading virtualization firm. One of VMware’s biggest competitors, Nutanix, claims to have swiped tens of thousands of VMware customers.

Speaking at a press briefing at Nutanix’s .NEXT conference in Chicago this week, Nutanix CEO Rajiv Ramaswami said that “about 30,000 customers” have migrated from VMware to the rival platform, pointing to customer disapproval over Broadcom’s VMware strategy, SDxCentral, a London-based IT publication, reported today.

“I think there’s no doubt that the customer sentiment continues to be negative about Broadcom,” Ramaswami said, per SDxCentral.

Since Broadcom acquired VMware in November 2023, numerous VMware users have sought to reduce or end their reliance on VMware technologies. The most common drivers for migrations are that VMware is getting too expensive; users are being forced to bundle products; the company ended perpetual licenses; and VMware has become harder to work with after Broadcom culled channel partners.

Broadcom’s strategy has made VMware unaffordable or impractical for most small- to medium-size businesses (SMBs) and narrowed VMware’s focus to enterprise-size customers.

Nutanix hasn’t specified how many of the customers that it got from VMware are SMBs or enterprise-sized; although, adoption is said to be strongest among mid-market customers as Nutanix also tries wooing larger customers, often by starting with partial deployments.

During this week’s press briefing, Ramaswami reportedly said that some of the customers that moved from VMware to Nutanix during the latter’s most recent fiscal quarter represented Nutanix’s “strongest quarterly new logo additions in eight years.”

“Most of the logos came from our typical VMware migrations on to the [hyperconverged infrastructure] platform,” he said.

During the Nutanix conference, Brandon Shaw, Nutanix VP and head of technology services, said that Western Union has been migrating from VMware to Nutanix for six months, The Register reported. The financial services company is moving 900 to 1,200 applications across 3,900 cores.

Shaw said that Western Union has been exploring new IT suppliers to help it become more customer-focused. Despite Broadcom’s history of “decent lines of communication” with Western Union, Shaw said that Western Union had “challenges partnering with them.”

https://arstechnica.com/information-technology/2026/04/nutanix-claims-it-has-poached-30000-vmware-customers/

Hackers working on behalf of the Iranian government are disrupting operations at multiple US critical infrastructure sites, likely in response to the country’s ongoing war with the US, a half-dozen government agencies are warning.

In an advisory published Tuesday, the FBI, Cybersecurity and Infrastructure Security Agency, National Security Agency, Environmental Protection Agency, Department of Energy, and US Cyber Command “urgently” warned that the APT, or advanced persistent threat group, is targeting PLCs, short for programmable logic controllers. These devices, typically the size of a toaster, sit in factories, water treatment centers, oil refineries, and other industrial settings, often in remote locations. They provide an interface between computers used for automation and physical machinery.

Operational disruption and financial loss

“Since at least March 2026, the authoring agencies identified (through engagements with victim organizations) an Iranian-affiliated APT-group that disrupted the function of PLCs,” the advisory stated. “These PLCs were deployed across multiple US critical infrastructure sectors (including Government Services and Facilities, Waste Water Systems (WWS), and Energy sectors) within a wide variety of industrial automation processes. Some of the victims experienced operational disruption and financial loss.”

Among the PLCs being compromised or targeted are those made by Rockwell Automation/Allen-Bradley. Security firm Censys said Wednesday that an Internet scan it performed identified 5,219 such devices exposed to the Internet. A full 75 percent of them were located in the US and likely in far-off locations where equipment is located. The infrastructure being used to target the devices is a “single multi-home Windows engineering workstation running the Rockwell tool chain.”

https://arstechnica.com/security/2026/04/iran-linked-hackers-disrupt-operations-at-us-critical-infrastructure-sites/