Description
In the Linux kernel, the following vulnerability has been resolved:

batman-adv: hold claim backbone gateways by reference

batadv_bla_add_claim() can replace claim->backbone_gw and drop the old
gateway's last reference while readers still follow the pointer.

The netlink claim dump path dereferences claim->backbone_gw->orig and
takes claim->backbone_gw->crc_lock without pinning the underlying
backbone gateway. batadv_bla_check_claim() still has the same naked
pointer access pattern.

Reuse batadv_bla_claim_get_backbone_gw() in both readers so they operate
on a stable gateway reference until the read-side work is complete.
This keeps the dump and claim-check paths aligned with the lifetime
rules introduced for the other BLA claim readers.
Published: 2026-04-24
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: Remote Code Execution
Action: Immediate Patch
AI Analysis

Impact

The vulnerability exists in the batman-adv module of the Linux kernel. The function batadv_bla_add_claim() can replace the claim-backbone_gw pointer and drop the reference to the previous gateway while another reader still holds the pointer. This results in a dangling or uninitialized reference that can be dereferenced by netlink claim dump or claim check paths. The exposed dereference can corrupt the kernel’s address space, yielding arbitrary code execution or a system crash. The weakness is identified as CWE-476 (Dereferenced Uninitialized Pointer).

Affected Systems

Affected kernels include Linux kernel 3.5 and all 7.0 release candidates from RC1 through RC7. Any system running these kernel versions with the batman-adv driver enabled is susceptible.

Risk and Exploitability

The CVSS score of 9.8 highlights criticality, while the EPSS score of less than 1% indicates that, as of the latest data, active exploitation is uncommon but still possible. The vulnerability is not yet listed in the CISA KEV catalog. Exploitation likely requires local privileges or a network packet that triggers the batman-adv netlink handler, as the flaw stems from a pointer misuse rather than a public-facing interface that can be called from unprivileged users. Administrators should treat this as a high-risk zero-day.

Generated by OpenCVE AI on April 28, 2026 at 13:46 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade to a Linux kernel version that includes the batadv reference counting fix (e.g., 7.1 or later).
  • If an update is not immediately available, disable batman-adv networking or bring associated interfaces down to prevent the vulnerable code from executing.
  • Apply the latest kernel patch from the Git kernel repository that addresses batadv_bla_add_claim() and related netlink handling.

Generated by OpenCVE AI on April 28, 2026 at 13:46 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DLA Debian DLA DLA-4561-1 linux-6.1 security update
Debian DSA Debian DSA DSA-6238-1 linux security update
Debian DSA Debian DSA DSA-6243-1 linux security update
History

Mon, 27 Apr 2026 20:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-476
CPEs cpe:2.3:o:linux:linux_kernel:3.5:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*

Mon, 27 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Sat, 25 Apr 2026 00:15:00 +0000


Fri, 24 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by reference batadv_bla_add_claim() can replace claim->backbone_gw and drop the old gateway's last reference while readers still follow the pointer. The netlink claim dump path dereferences claim->backbone_gw->orig and takes claim->backbone_gw->crc_lock without pinning the underlying backbone gateway. batadv_bla_check_claim() still has the same naked pointer access pattern. Reuse batadv_bla_claim_get_backbone_gw() in both readers so they operate on a stable gateway reference until the read-side work is complete. This keeps the dump and claim-check paths aligned with the lifetime rules introduced for the other BLA claim readers.
Title batman-adv: hold claim backbone gateways by reference
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T22:13:03.739Z

Reserved: 2026-03-09T15:48:24.129Z

Link: CVE-2026-31657

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-04-24T15:16:45.227

Modified: 2026-04-27T20:16:58.960

Link: CVE-2026-31657

cve-icon Redhat

Severity :

Publid Date: 2026-04-24T00:00:00Z

Links: CVE-2026-31657 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-28T14:00:16Z

Weaknesses