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CVE intelligence

CVE-2026-31657

Vulnerability intelligence

Published Apr 24, 2026Sources checked Oct 27, 2026
9.8CRITICALCVSS out of 10
What this means

Review the available evidence

CVE-2026-31657 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 25, 2026

CBL-Mariner Releases Release Notes

Vendor-listed releases

  • 6.6.137.1-1

Ubuntu Security Notices guidance

Vendor revision: Sep 18, 2026
Vendor remediation details

This update corrects flaws in the following subsystems: - x86 architecture; - Cryptographic API; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - NVME drivers; - File systems infrastructure; - Ext4 file system; - OCFS2 file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - B.A.T.M.A.N.

Ubuntu Security Notices guidance

Vendor revision: Sep 2, 2026
Vendor remediation details

This update corrects flaws in the following subsystems: - x86 architecture; - Cryptographic API; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - NVME drivers; - File systems infrastructure; - Ext4 file system; - OCFS2 file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - B.A.T.M.A.N.

CISA KEVNot listedBased on the latest collected catalog
EPSS0.4%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview

What is CVE-2026-31657?

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.

Source: NVD