CVE-2025-39816 Affecting kernel6.12-headers package, versions <1:6.12.53-69.119.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.02% (6th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL612HEADERS-13731150
  • published29 Oct 2025
  • disclosed16 Sept 2025

Introduced: 16 Sep 2025

CVE-2025-39816  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.12-headers to version 1:6.12.53-69.119.amzn2023 or higher.
This issue was patched in ALAS2023-2025-1254.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.12-headers package and not the kernel6.12-headers 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:

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.

CVSS Base Scores

version 3.1