CVE-2026-80758
futex: Avoid private hash use-after-free on final put
Description
In the Linux kernel, the following vulnerability has been resolved: futex: Avoid private hash use-after-free on final put futex_private_hash_put() drops the reference to fph before evaluating fph->mm for wake_up_var(). futex_ref_put() enables preemption again before returning. If that put drops the final reference and the task is preempted, another task can pivot to the replacement hash and free the old hash after an RCU grace period. The first task then reads fph->mm from the freed allocation when it resumes. KASAN reports a slab-use-after-free in futex_private_hash_put(), with the read at offset 24 in a freed kmalloc-512 allocation. The allocation and free stacks point to futex_hash_allocate() and the RCU free path, respectively. Load the mm pointer while the fph reference is still held and pass the saved value to wake_up_var(). wake_up_var() uses the pointer as a waitqueue key and does not dereference the mm through it.
INFO
Published Date :
Sept. 4, 2026, 4:18 p.m.
Last Modified :
Sept. 4, 2026, 4:18 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Update the Linux kernel to the latest version.
- Rebuild and install the patched kernel.
- Reboot the system to load the new kernel.
References to Advisories, Solutions, and Tools
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CVE-2026-80758.
CWE - Common Weakness Enumeration
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specific instances of vulnerabilities, CWE categorizes the common flaws or
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-80758
weaknesses.
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CVE-2026-80758 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-80758 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 04, 2026
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: futex: Avoid private hash use-after-free on final put futex_private_hash_put() drops the reference to fph before evaluating fph->mm for wake_up_var(). futex_ref_put() enables preemption again before returning. If that put drops the final reference and the task is preempted, another task can pivot to the replacement hash and free the old hash after an RCU grace period. The first task then reads fph->mm from the freed allocation when it resumes. KASAN reports a slab-use-after-free in futex_private_hash_put(), with the read at offset 24 in a freed kmalloc-512 allocation. The allocation and free stacks point to futex_hash_allocate() and the RCU free path, respectively. Load the mm pointer while the fph reference is still held and pass the saved value to wake_up_var(). wake_up_var() uses the pointer as a waitqueue key and does not dereference the mm through it. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/80xxx/CVE-2026-80758.json">CVE-2026-80758</a> Added Reference https://git.kernel.org/stable/c/12cd315a7b6a7d7db3f69d98bfe3909275e9451d Added Reference https://git.kernel.org/stable/c/1c7efabfbaf796f11000a46094a69955a01ec6cc Added Reference https://git.kernel.org/stable/c/25408c62ed4ebcd491d0e9e4b4a5b512547512e4 Added Reference https://git.kernel.org/stable/c/dba60d26e9dda3e157ad6b0934d4232f6c6904ee