CyberSecBulletin
CVE-2026-31449NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-31449 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 unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions 39d6e2b67651614bac0dc6592fa9836321910067, c5839b34704c9c2f47f079451bdbb22de0da1ed1, 10242e640b36b91ad03d25f3dc77854bbdff8358 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 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 39d6e2b67651614bac0dc6592fa9836321910067 or c5839b34704c9c2f47f079451bdbb22de0da1ed1 or 10242e640b36b91ad03d25f3dc77854bbdff8358 or 4d08401aa13f1531216f1a7ae281ca4806e90a5c, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.12.80 or 6.18.21 or 6.19.11, whichever matches your release line, or a later version.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxa86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 39d6e2b67651614bac0dc6592fa9836321910067; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, c5839b34704c9c2f47f079451bdbb22de0da1ed1; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 10242e640b36b91ad03d25f3dc77854bbdff8358; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 4d08401aa13f1531216f1a7ae281ca4806e90a5c; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 407c944f217c17d4343148011acafebc604d55e1; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 93f2e975ed658ce09db4d4c2877ca2c06540df83; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 01bf1e0b997d82c0e353b51ed74ef99698043c33; a86c61812637c7dd0c57e29880cffd477b62f2e7 up to, but not including, 2acb5c12ebd860f30e4faf67e6cc8c44ddfe5fe8; and 1 more ranges39d6e2b67651614bac0dc6592fa9836321910067, c5839b34704c9c2f47f079451bdbb22de0da1ed1, 10242e640b36b91ad03d25f3dc77854bbdff8358, 4d08401aa13f1531216f1a7ae281ca4806e90a5c, 407c944f217c17d4343148011acafebc604d55e1, 93f2e975ed658ce09db4d4c2877ca2c06540df83
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)V3.1.6 and later; V3.1.7 and laterNot stated
LinuxLinux Kernel2.6.19.1 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 2.6.19; 7.06.12.80, 6.18.21, 6.19.11

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
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
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:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: ext4: validate p_idx bounds in ext4_ext_correct_indexes ext4_ext_correct_indexes() walks up the extent tree correcting index entries when the first extent in a leaf is modified. Before accessing path[k].p_idx->ei_block, there is no validation that p_idx falls within the valid range of index entries for that level. If the on-disk extent header contains a corrupted or crafted eh_entries value, p_idx can point past the end of the allocated buffer, causing a slab-out-of-bounds read. Fix this by validating path[k].p_idx against EXT_LAST_INDEX() at both access sites: before the while loop and inside it. Return -EFSCORRUPTED if the index pointer is out of range, consistent with how other bounds violations are handled in the ext4 extent tree code.

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.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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