Time-of-check Time-of-use (TOCTOU) The advisory has been revoked - it doesn't affect any version of package kernel-headers (opens in a new tab)
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-RHEL10-KERNELHEADERS-12801283
- published17 Sept 2025
- disclosed16 Sept 2025
Introduced: 16 Sep 2025
CVE-2025-39816 (opens in a new tab)Amendment
The Red Hat security team deemed this advisory irrelevant for RHEL:10.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-headers package and not the kernel-headers package as distributed by RHEL.
In the Linux kernel, the following vulnerability has been resolved:
io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths
Since the buffers are mapped from userspace, it is prudent to use READ_ONCE() to read the value into a local variable, and use that for any other actions taken. Having a stable read of the buffer length avoids worrying about it changing after checking, or being read multiple times.
Similarly, the buffer may well change in between it being picked and being committed. Ensure the looping for incremental ring buffer commit stops if it hits a zero sized buffer, as no further progress can be made at that point.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=2395790
- https://access.redhat.com/security/cve/CVE-2025-39816
- https://git.kernel.org/stable/c/390a61d284e1ced088d43928dfcf6f86fffdd780
- https://git.kernel.org/stable/c/695673eb5711ee5eb1769481cf1503714716a7d1
- https://git.kernel.org/stable/c/98b6fa62c84f2e129161e976a5b9b3cb4ccd117b
- https://git.kernel.org/stable/c/91f262ea2a76a02d9e37dba6637cfe6feebb20a8