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CVE-2022-50095

HIGHCVSS 7.8/10EPSS 0.21%

Last modified

CVE-2022-50095 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Cleanup CPU timers before freeing them during exec Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") started looking up tasks by PID when deleting a CPU timer. When a non-leader thread calls execve, it will switch PIDs with the leader process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find the task because the timer still points out to the old PID. That means that armed timers won't be disarmed, that is, they won't be removed from the timerqueue_list. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Cleanup CPU timers before freeing them during exec Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") started looking up tasks by PID when deleting a CPU timer. When a non-leader thread calls execve, it will switch PIDs with the leader process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find the task because the timer still points out to the old PID. That means that armed timers won't be disarmed, that is, they won't be removed from the timerqueue_list. exit_itimers will still release their memory, and when that list is later processed, it leads to a use-after-free. Clean up the timers from the de-threaded task before freeing them. This prevents a reported use-after-free.

Metrics

CVSS 3.1
7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.21%

11.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
LinuxLinux Kernel>= 5.7, < 5.10.137
LinuxLinux Kernel>= 5.11, < 5.15.61
LinuxLinux Kernel>= 5.16, < 5.18.18
LinuxLinux Kernel>= 5.19, < 5.19.2

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2022-50095?
In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Cleanup CPU timers before freeing them during exec Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") started looking up tasks by PID when deleting a CPU timer. When a non-leader thread calls execve, it will switch PIDs with the leader process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find the task because the timer still points out to the old PID. That means that armed timers won't be disarmed, that is, they won't be removed from the timerqueue_list. exit_itimers will still release their memory, and when that list is later processed, it leads to a use-after-free. Clean up the timers from the de-threaded task before freeing them. This prevents a reported use-after-free.
How severe is CVE-2022-50095?
CVE-2022-50095 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.
How do I fix CVE-2022-50095?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST