CVE-2026-98260

Received Received - Intake

BaseFortify

Publication date: 2026-10-06

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: exec: Cleanup POSIX timers right after de_thread() A per-thread CPU timer holds a reference to the PID of the thread it is attached to and, while it is armed, its node is queued in that thread's posix_cputimers. The task is looked up by that PID. When a non-leader thread exec()s, de_thread() changes which task owns that PID. pid_task(timer->it.cpu.pid, PIDTYPE_PID) then returns NULL, but the node is still queued on tsk, which is alive. timer_lock_sighand() takes a failed lookup to mean that the node is already dequeued, so it has nothing to undo. begin_new_exec() calls posix_cpu_timers_exit(me) right after exec_task_namespaces() and that removes the leftover node, so the state normally stays invisible. But bprm->point_of_no_return is set before de_thread(), so if unshare_files(), set_mm_exe_file(), exec_mmap() or exec_task_namespaces() fails, the task dies before it gets there. exit_itimers() then frees the k_itimer while its node is still queued, and reaping tsk later erases that freed node from the rbtree. In short: the non-leader thread B the parent timer_create(CLOCK_THREAD_CPUTIME_ID) timer_settime() arm_timer() // the node is queued on B execve() de_thread(B) exchange_tids(B, leader) // B's PID now belongs to the leader release_task(leader) __exit_signal(leader) posix_cpu_timers_exit(leader) // cleans leader's queue, not B's __unhash_process(leader) // that PID has no task anymore exec_mmap() mmap_read_lock_killable(old_mm) kill(B, SIGKILL) // -EINTR get_signal() do_exit() exit_itimers() posix_timer_delete() posix_cpu_timer_del() posix_timer_unhash_and_free() // freed while still queued wait4() release_task(B) posix_cpu_timers_exit(B) cleanup_timerqueue() timerqueue_del() // use-after-free Move the POSIX timer cleanup right after de_thread() before any of the later failure conditions brings the task into do_exit(). [ tglx: Move the cleanup right after de_thread() ]

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-06

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-06

EPSS Evaluated

2026-10-18

NVD

CVE-2026-98260

EUVD

EUVD-2026-93188

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	55e8c8eb2c7b6bf30e99423ccfe7ca032f498f59
Linux	Linux	55e8c8eb2c7b6bf30e99423ccfe7ca032f498f59
Linux	Linux	55e8c8eb2c7b6bf30e99423ccfe7ca032f498f59
Linux	Linux	55e8c8eb2c7b6bf30e99423ccfe7ca032f498f59
Linux	Linux	55e8c8eb2c7b6bf30e99423ccfe7ca032f498f59
Linux	Linux	5.7

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a use-after-free vulnerability in the Linux kernel related to POSIX CPU timers. When a non-leader thread executes a new program, the kernel fails to properly clean up POSIX timers attached to the thread. This leads to a situation where a timer's node remains queued in a task's data structure even after the timer is freed, causing a use-after-free error when the task is reaped later.

Detection Guidance

This vulnerability is specific to the Linux kernel and requires kernel-level inspection. Detection involves checking kernel logs for crashes or unusual timer-related errors. Commands like dmesg, journalctl -k, or checking for kernel oops messages may help identify issues. No direct user-space commands detect this flaw.

Impact Analysis

This vulnerability could allow an attacker with local access to cause a denial-of-service condition or potentially execute arbitrary code with kernel privileges. It may lead to system crashes, data corruption, or unauthorized access depending on the attacker's capabilities and system configuration.

Compliance Impact

This vulnerability does not directly impact compliance with standards like GDPR or HIPAA as it is a low-level kernel issue related to POSIX timers and thread execution. Compliance implications would depend on system-specific configurations and whether the vulnerability leads to unauthorized access or data breaches.

Mitigation Strategies

Apply the latest Linux kernel patches from your distribution. Reboot the system to load the updated kernel. Monitor for crashes or timer-related errors post-update. Disable non-essential POSIX timers if immediate patching is not possible.

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