CVE-2026-31498

Medium

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop l2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED state to support L2CAP reconfiguration (e.g. MTU changes). However, since both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from the initial configuration, the reconfiguration path falls through to l2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and retrans_list without freeing the previous allocations and sets chan->sdu to NULL without freeing the existing skb. This leaks all previously allocated ERTM resources. Additionally, l2cap_parse_conf_req() does not validate the minimum value of remote_mps derived from the RFC max_pdu_size option. A zero value propagates to l2cap_segment_sdu() where pdu_len becomes zero, causing the while loop to never terminate since len is never decremented, exhausting all available memory. Fix the double-init by skipping l2cap_ertm_init() and l2cap_chan_ready() when the channel is already in BT_CONNECTED state, while still allowing the reconfiguration parameters to be updated through l2cap_parse_conf_req(). Also add a pdu_len zero check in l2cap_segment_sdu() as a safeguard.

Package Linux Kernel
Published 2026-04-22
Last modified 2026-04-28
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-835

CVE-2026-31498 is a Infinite Loop vulnerability

What is Infinite Loop?

The product contains an iteration that does not exit even when it should. Learn more on MITRE CWE

Affected versions

Linux kernel versions 4.4.238, 4.9.238, 4.14.200, 4.19.149, 5.4.69, 5.7 and later are affected. Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11, 7.0 and their respective stable series.

Affected from
≥ 4.4.238 ≥ 4.9.238 ≥ 4.14.200 ≥ 4.19.149 ≥ 5.4.69 ≥ 5.7
Fixed in
✓ 5.10.253 5.10.x ✓ 5.15.203 5.15.x ✓ 6.1.168 6.1.x ✓ 6.6.131 6.6.x ✓ 6.12.80 6.12.x ✓ 6.18.21 6.18.x ✓ 6.19.11 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31498 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-31498?

    CVE-2026-31498 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as an Infinite Loop flaw (CWE-835) . It affects Linux kernel versions from 4.4.238 onward and has been patched in 5.10.253, 5.15.203, 6.1.168 and others. CVE-2026-31498 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-31498?

    CVE-2026-31498 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-31498?

    Yes — CVE-2026-31498 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.168 and others. If you are running Linux kernel 4.4.238 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-31498 actively exploited?

    No — CVE-2026-31498 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Infinite Loop (CWE-835)?

    The product contains an iteration that does not exit even when it should. View CWE-835 on MITRE CWE →

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