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This Week In Security: Another Linux Exploit, Ubuntu Knocked Offline, Finals Interrupted, And Backdoored Tools

May 8, 2026 by 15 Comments

After the CopyFail vulnerability gave root access from any user on almost all distributions last week, this week we’ve got DirtyFrag. This chains the vulnerability in CopyFail (xfrm-ESP) and a new vulnerability in a RPC function which allows similar overwriting of the page cache.

Both vulnerabilities manipulate the Linux page cache where data from disk is stored for rapid access. The kernel will always prefer the cached version of a file, which means that anything that is able to manipulate the contents of the cache can effectively replace the contents of the file. Both of the vulnerabilities leverage a similar mechanism – picking a binary which is flagged to run as root, such as su, and replacing the contents that would prompt for the users password with a launcher to immediately run a shell.

Like CopyFail, DirtyFrag requires the ability to execute code on the target in the first place, but turning almost any code or command execution vulnerability in any network service into root raises the impact significantly, allowing an attacker to break out of containers and privilege environments, or establish a persistent presence in the system when the original vulnerabilities are discovered and closed.

The previous mitigations to block specific kernel modules related to CopyFail are not sufficient to block the new vulnerabilities. At the time of writing this, there are no available patches from the distributions, however the vulnerable kernel modules can be temporarily disabled.

CopyFail added to KEV

CISA (the United States cyber security agency) has added CopyFail to the KEV, or Known Exploited Vulnerabilities list. Attacks on the KEV have been observed under active exploitation, which in the case of CopyFail is hardly a surprise.

The KEV is designed as a tool to allow security teams in government and commercial industry to prioritize the highest risk vulnerabilities – or at least give another source of data to point at when you say “we really need to patch this now”.

Prolonged Ubuntu DDOS

On the heels of the CopyFail vulnerability impacting almost all distributions, Ubuntu has had to face a prolonged distributed denial-of-service (DDoS) attack against the main infrastructure. Ars Technica reported at the beginning of the attack, and after several days, services appear to be restored. In the meantime, core services such as package updates, core repositories, and even the Ubuntu and Canonical websites were largely unreachable.

An Iraqi group claims responsibility for the attack, but it is unclear if they were the actual perpetrators – or why. The timing with the CopyFail vulnerability seems like an opportune moment to cause chaos by taking the update mechanisms of a major distribution offline, but in the era of modern Internet behavior, it could also just have been a Tuesday.

Continue reading “This Week In Security: Another Linux Exploit, Ubuntu Knocked Offline, Finals Interrupted, And Backdoored Tools” →

This Week In Security: State Malware, State Hardware Bans, And Stuxnet Before Stuxnet Was Cool

May 1, 2026 by 8 Comments

Making headlines everywhere is the CopyFail Linux kernel vulnerability, which allows local privilege escalation (LPE) from any user to root privileges on most kernels and distributions.

Local privileges escalations are never good, but typically are not “Internet-melters”: they are significantly less dangerous than remote vulnerabilities, but are often combined with a remote vulnerability to gain complete access to a system.

This time, the vulnerability is in the Linux kernel handling of cryptographic functions used in IPSec. The mistake allows writing into the in-memory cache of file data; this allows modifying what the system thinks a file contains, without ever touching the contents of the actual file. Coupled with a suid binary — a binary configured to always run as root, no matter what user starts it — the binary can be modified to run any code as root. In this case, that means launching a new interactive shell. Nearly every distribution includes several standard suid binaries, such as the command su which requires root privileges to switch users.

The bug is pervasive, impacting kernels from 2017, and can be triggered on any distribution where the IPSec kernel modules are enabled and loaded, which is the vast majority of them. Kernel patches are available, and most distributions should have them at this point. For the average home user, you’ll want to upgrade as soon as is practical; for services with untrusted users or containerized systems which might run untrusted workloads, if updating immediately is not practical, Theori has mitigation suggestions on the blog post. Continue reading “This Week In Security: State Malware, State Hardware Bans, And Stuxnet Before Stuxnet Was Cool” →