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CVE-2026-43499

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.261, 5.15.212, 6.1.175, 6.6.140, 6.12.86, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: poc
  • Automatable: no
  • Technical impact: total

Summary

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 ]

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in f3fa3424bceb128d2be4b3745506b22844b87db7; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in d8cce4773c2b23d819baf5abedc62f7b430e8745; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 8a1fc8d698ac5e5916e3082a0f74450d71f9611f; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 6d52dfcb2a5db86e346cf51f8fcf2071b8085166; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 3fb7394a837740770f0d6b4b30567e60786a63f2; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 88614876370aac8ad1050ad785a4c095ba17ac11; From 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 · fixed in 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349

  • Linux Linux

    2.6.39

  • KernelLinux

    From 2.6.39 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.175; From 6.2.0 · fixed in 6.6.140; From 6.7.0 · fixed in 6.12.86; From 6.13.0 · fixed in 6.18.27; From 6.19.0 · fixed in 7.0.4

References 8

git.kernel.org