Linux: Out-of-bounds Read
CVE-2025-21789 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 964a8895704a22efc06a2a3276b624a5ae985a06, 9f15a8df542c0f08732a67d1a14ee7c22948fb97, d6508ffff32b44b6d0de06704034e4eef1c307a7 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 0.23% 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 964a8895704a22efc06a2a3276b624a5ae985a06 or 9f15a8df542c0f08732a67d1a14ee7c22948fb97 or d6508ffff32b44b6d0de06704034e4eef1c307a7 or 6287f1a8c16138c2ec750953e35039634018c84a, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.79 or 6.12.16 or 6.13.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 69e3a6aa6be21de6aaf38130fad97ecde34a193c up to, but not including, 964a8895704a22efc06a2a3276b624a5ae985a06; 69e3a6aa6be21de6aaf38130fad97ecde34a193c up to, but not including, 9f15a8df542c0f08732a67d1a14ee7c22948fb97; 69e3a6aa6be21de6aaf38130fad97ecde34a193c up to, but not including, d6508ffff32b44b6d0de06704034e4eef1c307a7; 69e3a6aa6be21de6aaf38130fad97ecde34a193c up to, but not including, 6287f1a8c16138c2ec750953e35039634018c84a; 6.4 | 964a8895704a22efc06a2a3276b624a5ae985a06, 9f15a8df542c0f08732a67d1a14ee7c22948fb97, d6508ffff32b44b6d0de06704034e4eef1c307a7, 6287f1a8c16138c2ec750953e35039634018c84a |
| Linux | Linux Kernel | 6.4 up to, but not including, 6.6.79; 6.7 up to, but not including, 6.12.16; 6.13 up to, but not including, 6.13.4; 6.14 | 6.6.79, 6.12.16, 6.13.4 |
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 | 7.3 | High | CNA |
| CVSS 3.1 | 7.1 | High | NVD |
| CVSS 3.1 | 7.1 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: csum: Fix OoB access in IP checksum code for negative lengths Commit 69e3a6aa6be2 ("LoongArch: Add checksum optimization for 64-bit system") would cause an undefined shift and an out-of-bounds read. Commit 8bd795fedb84 ("arm64: csum: Fix OoB access in IP checksum code for negative lengths") fixes the same issue on ARM64.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/6287f1a8c16138c2ec750953e35039634018c84aMailing List
- git.kernel.org/stable/c/964a8895704a22efc06a2a3276b624a5ae985a06Mailing List
- git.kernel.org/stable/c/9f15a8df542c0f08732a67d1a14ee7c22948fb97Mailing List
- git.kernel.org/stable/c/d6508ffff32b44b6d0de06704034e4eef1c307a7Mailing List
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
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