CVE-2026-90203 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-LINUX612-20507314
- published5 Oct 2026
- disclosed17 Sept 2026
Introduced: 17 Sep 2026
NewCVE-2026-90203 (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:
Squashfs: check block offset is not negative
If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfs_copy_data() to perform an out of bounds access.
Fix by checking if offset is negative, and returning 0. This matches existing behaviour where an offset beyond the block returns 0 bytes copied.
To trigger this out of bounds access requires a crafted Squashfs filesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be able to mount such a filesystem, but once mounted, an unprivileged user can trigger the out of bounds access by reading the crafted file with the negative offset.
References
- https://security-tracker.debian.org/tracker/CVE-2026-90203
- https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84
- https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd
- https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88
- https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344
- https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b
- https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03
- https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e
- https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe