Linux: Out-of-bounds Read
CVE-2025-21946 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions f4ee19528664777af8b842f8f001be98345aa973, c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b, 159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.5% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to f4ee19528664777af8b842f8f001be98345aa973 or c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b or 159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1 or 6a9831180d0b23b5c97e2bd841aefc8f82900172, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.83 or 6.12.19 or 6.13.7, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, f4ee19528664777af8b842f8f001be98345aa973; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, 159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, 6a9831180d0b23b5c97e2bd841aefc8f82900172; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, d6e13e19063db24f94b690159d0633aaf72a0f03; 5.15 | f4ee19528664777af8b842f8f001be98345aa973, c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b, 159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1, 6a9831180d0b23b5c97e2bd841aefc8f82900172, d6e13e19063db24f94b690159d0633aaf72a0f03 |
| Linux | Linux Kernel | 5.15 up to, but not including, 6.6.83; 6.7 up to, but not including, 6.12.19; 6.13 up to, but not including, 6.13.7; 6.14 | 6.6.83, 6.12.19, 6.13.7 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds in parse_sec_desc() If osidoffset, gsidoffset and dacloffset could be greater than smb_ntsd struct size. If it is smaller, It could cause slab-out-of-bounds. And when validating sid, It need to check it included subauth array size.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
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