Homepage

CVE-2026-93203 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.41% (33rd percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-DEBIAN12-LINUX612-20507310
  • published5 Oct 2026
  • disclosed17 Sept 2026
Report a new vulnerability Found a mistake?

Introduced: 17 Sep 2026

NewCVE-2026-93203  (opens in a new tab)

How to fix?

Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

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

batman-adv: bla: avoid CRC corruption due to parallel claim add

batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either

  • add the new claim's CRC to the backbone CRC
  • remove the already existing claim's CRC from the old backbone and add it to the new backbone

But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path:

  • CPU0 creates the claim for gateway A and publishes it in the claim hash. The crc16 of the address has not yet been added to A's crc at this point.

  • CPU1 processes a claim frame of gateway B for the same client, finds the just published claim, and performs the ownership change: it switches the pointer to B, removes the crc16 from A's crc - which never contained it - and adds it to B's crc.

  • CPU0 continues behind the creation branch, unconditionally switches the pointer back to A without compensating B's crc (its remove_crc is false for the creation path), and finally adds the crc16 to A's crc

The CRC is then wrong for both:

  • claim belongs to A: but CRC is not part of backbone A's CRC
  • claim doesn't belong to B: CRC is still part of backbone B's CRC

This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs.

To avoid this, split the functionality in clear separate parts:

  • new claim which always adds claim CRC to the backbone CRC (but never changes the already set backbone_gw of the claim back)

  • update of existing claim which automatically changes the backbone_gw entry and only updates both backbone CRCs when there was an actual change