Linux: Out-of-bounds Read
CVE-2025-21815 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 4491159774d973a9e2e998d25d8fbb20fada6dfa, 10b7d3eb535098ccd4c82a182a33655d8a0e5c88, d1366e74342e75555af2648a2964deb2d5c92200 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 0.19% 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 4491159774d973a9e2e998d25d8fbb20fada6dfa or 10b7d3eb535098ccd4c82a182a33655d8a0e5c88 or d1366e74342e75555af2648a2964deb2d5c92200, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.14 or 6.13.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3da0272a4c7d0d37b47b28e87014f421296fc2be up to, but not including, 4491159774d973a9e2e998d25d8fbb20fada6dfa; 3da0272a4c7d0d37b47b28e87014f421296fc2be up to, but not including, 10b7d3eb535098ccd4c82a182a33655d8a0e5c88; 3da0272a4c7d0d37b47b28e87014f421296fc2be up to, but not including, d1366e74342e75555af2648a2964deb2d5c92200; 6.7 | 4491159774d973a9e2e998d25d8fbb20fada6dfa, 10b7d3eb535098ccd4c82a182a33655d8a0e5c88, d1366e74342e75555af2648a2964deb2d5c92200 |
| Linux | Linux Kernel | 6.7 up to, but not including, 6.12.14; 6.13 up to, but not including, 6.13.3 | 6.12.14, 6.13.3 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: mm/compaction: fix UBSAN shift-out-of-bounds warning syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order) in isolate_freepages_block(). The bogus compound_order can be any value because it is union with flags. Add back the MAX_PAGE_ORDER check to fix the warning.
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
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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