CVE-2026-31662

High

In the Linux kernel, the following vulnerability has been resolved: tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements bc_ackers on every inbound group ACK, even when the same member has already acknowledged the current broadcast round. Because bc_ackers is a u16, a duplicate ACK received after the last legitimate ACK wraps the counter to 65535. Once wrapped, tipc_group_bc_cong() keeps reporting congestion and later group broadcasts on the affected socket stay blocked until the group is recreated. Fix this by ignoring duplicate or stale ACKs before touching bc_acked or bc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and prevents the underflow path.

Package Linux Kernel
Published 2026-04-24
Last modified 2026-04-27
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.5

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

Weakness type

CWE-191

CVE-2026-31662 is classified as CWE-191

See CWE-191 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 4.15 and later are affected. Fixed in 5.10.253, 5.15.203, 6.1.169, 6.6.135, 6.12.82, 6.18.23, 6.19.13, 7.0 and their respective stable series.

Affected from
≥ 4.15
Fixed in
✓ 5.10.253 5.10.x ✓ 5.15.203 5.15.x ✓ 6.1.169 6.1.x ✓ 6.6.135 6.6.x ✓ 6.12.82 6.12.x ✓ 6.18.23 6.18.x ✓ 6.19.13 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31662 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-2026-31662?

    CVE-2026-31662 is a High severity Linux kernel vulnerability with a CVSS score of 7.5 out of 10 . It affects Linux kernel versions from 4.15 onward and has been patched in 5.10.253, 5.15.203, 6.1.169 and others. CVE-2026-31662 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-31662?

    CVE-2026-31662 has a CVSS score of 7.5 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-31662?

    Yes — CVE-2026-31662 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.169 and others. If you are running Linux kernel 4.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-31662 actively exploited?

    No — CVE-2026-31662 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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