CVE-2025-39816: linux
Vulnerability summary
CVE-2025-39816 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 3.6% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 8 · Related 8Timeline
- 16-09-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.15%
Chance of exploitation in the next 30 days
Percentile
4%
Versus all other CVEs
30-day change
0.00 pp
From 0.14% on 22-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Ubuntu94 products
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
- linux-aws-5.13All versions (No fix recorded)
- linux-aws-5.19All versions (No fix recorded)
Linux2 products
- linux≥ ae98dbf43d755b4e111fcd086e53939bef3e9a1a, < 695673eb5711ee5eb1769481cf1503714716a7d1 | ≥ ae98dbf43d755b4e111fcd086e53939bef3e9a1a, < 91f262ea2a76a02d9e37dba6637cfe6feebb20a8 | ≥ ae98dbf43d755b4e111fcd086e53939bef3e9a1a, < 390a61d284e1ced088d43928dfcf6f86fffdd780 | ≥ ae98dbf43d755b4e111fcd086e53939bef3e9a1a, < 98b6fa62c84f2e129161e976a5b9b3cb4ccd117b | 6.12
- linux_kernel≥ 6.12, < 6.12.49 | ≥ 6.13, < 6.16.5 | 6.17:rc1 | 6.17:rc2 | 6.17:rc3
Debian1 product
- linux< 6.12.57-1 | < 6.16.5-1
3 vendors · 97 products
