CVE-2026-31657
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2026-31657
Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2026-31657.html
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/f4858832ddef2f39f21e30b7226bbcd3c4b2bc96
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/82d8701b2c930d0e96b0dbc9115a218d791cb0d2
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/7962b522222628596ca9ecc8722efc95367aadbd
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/4dee4c0688443aaf5bbec74aa203c851d1d53c35
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/2f55b58b5a0bbed192d60c444a45a49cdf1b545f
Vendor advisory: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 — https://git.kernel.org/stable/c/1f2dc36c297d27733f1b380ea644cf15a361bd7b
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | fixed | 6.1.170-1 |
| debian | forky | fixed | 6.19.13-1 |
| debian | sid | fixed | 6.19.13-1 |
| debian | trixie | fixed | 6.12.85-1 |
| debian | bullseye | fixed | 6.1.170-1~deb11u1 |
| linux-kernel | affected | 6.1.169 | |
| linux-kernel | 3.5 | affected | |
| linux-kernel | 7.0 | affected | |
References
- https://git.kernel.org/stable/c/1f2dc36c297d27733f1b380ea644cf15a361bd7b
- https://git.kernel.org/stable/c/2f55b58b5a0bbed192d60c444a45a49cdf1b545f
- https://git.kernel.org/stable/c/4dee4c0688443aaf5bbec74aa203c851d1d53c35
- https://git.kernel.org/stable/c/7962b522222628596ca9ecc8722efc95367aadbd
- https://git.kernel.org/stable/c/82d8701b2c930d0e96b0dbc9115a218d791cb0d2
- https://git.kernel.org/stable/c/f4858832ddef2f39f21e30b7226bbcd3c4b2bc96
- https://www.suse.com/security/cve/CVE-2026-31657.html
- https://security-tracker.debian.org/tracker/CVE-2026-31657
CWEs
CWE-476
Verify integrity in audit chain (admin only). AS-IS.