CVE-2026-90203

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.

CVSS 3.1

7.1CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 6% of CVEs (scores of 2026-10-25)

Published

2026-09-17

Modified

2026-10-19

Record from

the NVD, synced 2026-10-19

References

• 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

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