CVE-2026-98258

High

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list Kijo analyzed another race in the POSIX CPU timer code: Commit bf635681c906 converted cpu_timer::firing from a tristate value to a boolean. This lost the distinction between "not owned by the firing list" and "still owned, but delivery was canceled". The resulting race is: expiry handler timer_settime() timer_delete() -------------- --------------- -------------- collect timer onto private firing list firing = true observes firing = true firing = false return TIMER_RETRY wait for handler observes firing = false finish deletion unhash and free timer resume list traversal read freed elist.next -> UAF The firing bit is clearly the wrong indicator since that commit. Check whether the timer is queued on the expiry list or not instead. If it is queued clear the firing bit to prevent signal delivery as before and return TIMER_RETRY so the caller unlocks the timer which allows the expiry code to make progress and remove it from the list.

Package Linux Kernel
Published 2026-10-06
Last modified 2026-10-07
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 6.13 and later are affected. Fixed in 6.18.54, 7.2.8, 7.3-rc4 and their respective stable series.

Affected from
≥ 6.13
Fixed in
✓ 6.18.54 6.18.x ✓ 7.2.8 7.2.x ✓ 7.3-rc4

References

3 total

Frequently asked questions

  • What is CVE-2026-98258?

    CVE-2026-98258 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 . It affects Linux kernel versions from 6.13 onward and has been patched in 6.18.54, 7.2.8 and 7.3-rc4. CVE-2026-98258 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-98258?

    CVE-2026-98258 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2026-98258?

    Yes. CVE-2026-98258 has been patched. Fixed versions include 6.18.54, 7.2.8 and 7.3-rc4. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-98258 actively exploited?

    No. CVE-2026-98258 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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