CVE-2026-89951 (CVSS 8.8)

Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix stale receive device on merged fragments Fragment reassembly reuses the skb from the highest-numbered buffered fragment as the merged packet. When that fragment was received on a hard interface which is deleted before the chain completes, the merged skb can re-enter the receive path with a stale skb->dev and skb_iif. batadv_batman_skb_recv() passes such merged packets through the normal receive handlers again. DAT and bridge loop avoidance both derive the ARP header length from skb->dev, so they can dereference the freed net_device before the packet reaches the local mesh interface. Refresh the receive device metadata from the current receive device before running the packet handlers. This keeps internally reinjected merged fragments consistent with the normal receive path after hard interface teardown.

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CVSS v3.1 Score

8.8

HIGH

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

References

Other References

https://git.kernel.org/stable/c/2dffc8c44b6e3347b3719c6419c07b4a18fea895 https://git.kernel.org/stable/c/63d86250fa7cbe22451369bd1c0881dfc8190958 https://git.kernel.org/stable/c/6df64825f8b199921120c685af2abca14b077331 https://git.kernel.org/stable/c/a2c272da99c2077088083c14961cf2f1e4506995 https://git.kernel.org/stable/c/ad46c907d7d9975a285c1e89a4adde652eaa93f5 https://git.kernel.org/stable/c/e91d2cc7441d89a45bad73ad9789159c7441cb80 https://git.kernel.org/stable/c/f4b4ae763b5d59319fad62a00c76676758e7dafa https://git.kernel.org/stable/c/f830c2dfc1431764db9256b3d5db1695fc9a7f56

Frequently Asked Questions

What is CVE-2026-89951? +

In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix stale receive device on merged fragments Fragment reassembly reuses the skb from the highest-numbered buffered fragment as the merged packet. When that fragment was received on a hard interface which is deleted before the chain completes, the merged skb can re-enter the receive path with a stale skb->dev and skb_iif. batadv_batman_skb_recv() passes such merged packets through the normal receive handlers again. DAT and bridge loop avoidance both derive the ARP header length from skb->dev, so they can dereference the freed net_device before the packet reaches the local mesh interface. Refresh the receive device metadata from the current receive device before running the packet handlers. This keeps internally reinjected merged fragments consistent with the normal receive path after hard interface teardown. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-89951? +

CVE-2026-89951 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-89951? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-89951

Description

CVSS v3.1 Score

References

Other References

Frequently Asked Questions

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