CVE-2026-80775 Affecting kernel6.18-tools-debuginfo package, versions <1:6.18.48-107.148.amzn2023
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEBUGINFO-20249613
- published29 Sept 2026
- disclosed4 Sept 2026
Introduced: 4 Sep 2026
NewCVE-2026-80775 (opens in a new tab)How to fix?
Upgrade Amazon-Linux:2023 kernel6.18-tools-debuginfo to version 1:6.18.48-107.148.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3139.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-debuginfo package and not the kernel6.18-tools-debuginfo package as distributed by Amazon-Linux.
See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
futex: Fix race on the initial mm->futex.phash.ref allocation
futex_hash_allocate() allocates mm->futex.phash.ref without any locking. Commit d9b05321e21e ("futex: Move futex_hash_free() back to __mmput()") moved the allocation here and assumed that the process has just a single thread at this point.
Commit ee9dce44362b ("futex: Drop CLONE_THREAD requirement for private default hash alloc") widened need_futex_hash_allocate_default() to cover any CLONE_VM clone, but left out vfork because the parent is suspended and cannot race.
That no longer holds once vfork is nested. If a vfork child calls vfork again and is then killed with SIGKILL, the parent is released from its vfork wait and runs concurrently with the grandchild in the same mm. Neither of them went through futex_hash_allocate_default().
When both call prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS) at the same time, each one sees mm->futex.phash.ref as NULL and stores its own percpu counter. Only the last store survives. The counter stored first is no longer reachable from the mm, so the references on it are not seen by __futex_ref_atomic_end(). A private hash that still has references is then considered dead and freed, and a task that still holds one of its buckets writes into freed memory in futex_q_lock().
Store the counter once with cmpxchg() and let the loser free_percpu() its own. The initial reference has to be taken before the store, otherwise another task can install a private hash while the counter is still 0.
References
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-80775
- https://git.kernel.org/stable/c/86d12b34bafc9a4c271a9edefea88855a934d6e5
- https://git.kernel.org/stable/c/bde0238083647381d4747355c5a19115a3422b96
- https://git.kernel.org/stable/c/c4b4972d8edcdf50b6518f55119e129d2f668a10
- https://git.kernel.org/stable/c/ff252ed45c8263525f2f54d81c5fa6d547fba344