CyberSecBulletin
CVE-2026-31393NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-31393 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 187e6fe939295be36063a1d91f8bebee04399a8c, 5229e7d15771eac2b5886bfb1f976aea0c1eec14, 3b646516cba2ebc4b51a72954903326e7c1e443f 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 0.27% 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 187e6fe939295be36063a1d91f8bebee04399a8c or 5229e7d15771eac2b5886bfb1f976aea0c1eec14 or 3b646516cba2ebc4b51a72954903326e7c1e443f or 807bd1258453c4c83f6ae9dbc1e7b44860ff40d0, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.167 or 6.6.130, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, 187e6fe939295be36063a1d91f8bebee04399a8c; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, 5229e7d15771eac2b5886bfb1f976aea0c1eec14; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, 3b646516cba2ebc4b51a72954903326e7c1e443f; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, 807bd1258453c4c83f6ae9dbc1e7b44860ff40d0; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, 9aeacde4da0f02d42fd968fd32f245828b230171; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, e7ff754e339e3d5ce29aa9f95352d0186df8fbd9; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, db2872d054e467810078e2b9f440a5b326a601b2; 4e8402a3f884427f9233ba436459c158d1f2e114 up to, but not including, dd815e6e3918dc75a49aaabac36e4f024d675101; and 1 more ranges187e6fe939295be36063a1d91f8bebee04399a8c, 5229e7d15771eac2b5886bfb1f976aea0c1eec14, 3b646516cba2ebc4b51a72954903326e7c1e443f, 807bd1258453c4c83f6ae9dbc1e7b44860ff40d0, 9aeacde4da0f02d42fd968fd32f245828b230171, e7ff754e339e3d5ce29aa9f95352d0186df8fbd9
LinuxLinux Kernel2.6.24 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.20; 6.19 up to, but not including, 6.19.10; 7.05.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20

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
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
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:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access l2cap_information_rsp() checks that cmd_len covers the fixed l2cap_info_rsp header (type + result, 4 bytes) but then reads rsp->data without verifying that the payload is present: - L2CAP_IT_FEAT_MASK calls get_unaligned_le32(rsp->data), which reads 4 bytes past the header (needs cmd_len >= 8). - L2CAP_IT_FIXED_CHAN reads rsp->data[0], 1 byte past the header (needs cmd_len >= 5). A truncated L2CAP_INFO_RSP with result == L2CAP_IR_SUCCESS triggers an out-of-bounds read of adjacent skb data. Guard each data access with the required payload length check. If the payload is too short, skip the read and let the state machine complete with safe defaults (feat_mask and remote_fixed_chan remain zero from kzalloc), so the info timer cleanup and l2cap_conn_start() still run and the connection is not stalled.

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: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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