All vulnerabilities
CVE-2026-43499

Linux: rtmutex: Use waiter::task instead of current in remove_waiter()

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
7.8High
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 22 Aug 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.79%Chance of exploitation activity in the next 30 days, higher than 55% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in838ce5cb5d93c3ab8b27e75bc6ad905a94b752fdAlso 8a1fc8d698ac5e5916e3082a0f74450d71f9611f, 6d52dfcb2a5db86e346cf51f8fcf2071b8085166 and 3 moreCVE List
Published21 May 2026Updated 15 Oct 2026CVE List

What fixes it

  • 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fdLinuxCVE List
  • 8a1fc8d698ac5e5916e3082a0f74450d71f9611fLinuxCVE List
  • 6d52dfcb2a5db86e346cf51f8fcf2071b8085166LinuxCVE List
  • 3fb7394a837740770f0d6b4b30567e60786a63f2LinuxCVE List
  • 88614876370aac8ad1050ad785a4c095ba17ac11LinuxCVE List
  • 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 21 May 2026, 12:17 UTCPublishedCVE List
  2. 23 Oct 2026, 06:09 UTCExploit code publicGitHub proof-of-concept repositories

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

In the Linux kernel, the following vulnerability has been resolved:

rtmutex: Use waiter::task instead of current in remove_waiter()

remove_waiter() is used by the slowlock paths, but it is also used for proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from futex_requeue().

In the latter case waiter::task is not current, but remove_waiter() operates on current for the dequeue operation. That results in several problems:

1) the rbtree dequeue happens without waiter::task::pi_lock being held

2) the waiter task's pi_blocked_on state is not cleared, which leaves a dangling pointer primed for UAF around.

3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter task

Use waiter::task instead of current in all related operations in remove_waiter() to cure those problems.

[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the changelog ]

Text from CVE List

Affected versions 18

  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before f3fa3424bceb128d2be4b3745506b22844b87db7CVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fdCVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before d8cce4773c2b23d819baf5abedc62f7b430e8745CVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 8a1fc8d698ac5e5916e3082a0f74450d71f9611fCVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 6d52dfcb2a5db86e346cf51f8fcf2071b8085166CVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 3fb7394a837740770f0d6b4b30567e60786a63f2CVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 88614876370aac8ad1050ad785a4c095ba17ac11CVE List
  • Linuxaffected: 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 before 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349CVE List
  • Linuxaffected: 2.6.39CVE List
  • Linuxunaffected: all versions before 2.6.39CVE List
  • Linuxunaffected: 5.10.261 through 5.10.*CVE List
  • Linuxunaffected: 5.15.212 through 5.15.*CVE List
  • Linuxunaffected: 6.1.175 through 6.1.*CVE List
  • Linuxunaffected: 6.6.140 through 6.6.*CVE List
  • Linuxunaffected: 6.12.86 through 6.12.*CVE List
  • Linuxunaffected: 6.18.27 through 6.18.*CVE List
  • Linuxunaffected: 7.0.4 through 7.0.*CVE List
  • Linuxunaffected: 7.1CVE List

References 11