🛡️ CVE-2025-39816 on Debian — linux

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

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.

Distribution advisory

This page covers CVE-2025-39816 as tracked by Debian, for the package linux. The fix is available in version 6.16.5-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

DEBIAN-CVE-2025-39816 is recorded against 1 package.

linux (fixed in 6.16.5-1)

Timeline and source

Published on 16 September 2025 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2025-39816 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

BellSoft Base record Debian 13 (Root.io)Ubuntu

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2025-09-16

Updated 2026-08-20

Modified 2026-08-04

Fix URL N/A

Affected Packages

Software	From version	Fixed in
linux	—	6.16.5-1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2025-39816

🔗 NVD 🔗 Mitre

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