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Vulnerability record · CVE-2026-31657 · published 24 April 2026

CVE-2026-31657: Linux kernel null pointer dereference vulnerability

Linux · Linux Kernel

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.

9.8 CVSS 3.1 Critical EPSS 0.76% · top 46.7% CWE-476 · NULL pointer dereference
9.8CVSS 3.1 base score
0.76%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/1f2dc36c297d27733f1b380ea644cf15a361bd7b Patch
https://git.kernel.org/stable/c/2f55b58b5a0bbed192d60c444a45a49cdf1b545f Patch
https://git.kernel.org/stable/c/4dee4c0688443aaf5bbec74aa203c851d1d53c35 Patch
https://git.kernel.org/stable/c/5202f071b367ffbc8e279fc7a00db14f5e587f52
https://git.kernel.org/stable/c/69d1ce9c72eca91203ffdb8d08bacd511100aec6
https://git.kernel.org/stable/c/7962b522222628596ca9ecc8722efc95367aadbd Patch
https://git.kernel.org/stable/c/82d8701b2c930d0e96b0dbc9115a218d791cb0d2 Patch
https://git.kernel.org/stable/c/f4858832ddef2f39f21e30b7226bbcd3c4b2bc96 Patch

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Source: NIST National Vulnerability Database (record CVE-2026-31657), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.