Linux: Out-of-bounds Read
CVE-2026-31641 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 3e04596cba8a86cbff9c3f4bf0a524a3a488773c, 49875b360c2b83a3c226e189c502e501d83e6445, d179a868dd755b0cfcf7582e00943d702b9943b8 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 0.14% 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 3e04596cba8a86cbff9c3f4bf0a524a3a488773c or 49875b360c2b83a3c226e189c502e501d83e6445 or d179a868dd755b0cfcf7582e00943d702b9943b8, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.23 or 6.19.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0ca100ff4df64f5d0f6c1dd5080c3e096786bea6 up to, but not including, 3e04596cba8a86cbff9c3f4bf0a524a3a488773c; 0ca100ff4df64f5d0f6c1dd5080c3e096786bea6 up to, but not including, 49875b360c2b83a3c226e189c502e501d83e6445; 0ca100ff4df64f5d0f6c1dd5080c3e096786bea6 up to, but not including, d179a868dd755b0cfcf7582e00943d702b9943b8; 6.16 | 3e04596cba8a86cbff9c3f4bf0a524a3a488773c, 49875b360c2b83a3c226e189c502e501d83e6445, d179a868dd755b0cfcf7582e00943d702b9943b8 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Linux | Linux Kernel | 6.16.1 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 6.16; 7.0 | 6.18.23, 6.19.13 |
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
- HighData or code can be modified at will.
- 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:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.3 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix RxGK token loading to check bounds rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length from the XDR token as u32 values and passes each through round_up(x, 4) before using the rounded value for validation and allocation. When the raw length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and kzalloc both use 0 while the subsequent memcpy still copies the original ~4 GiB value, producing a heap buffer overflow reachable from an unprivileged add_key() call. Fix this by: (1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX. (2) Sizing the flexible-array allocation from the validated raw key length via struct_size_t() instead of the rounded value. (3) Caching the raw lengths so that the later field assignments and memcpy calls do not re-read from the token, eliminating a class of TOCTOU re-parse. The control path (valid token with lengths within bounds) is unaffected.
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
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
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