CVE-2026-90203

High CVSS 7.1

Published 2026-09-17 · last changed 2026-09-18

The fix

We hold no Microsoft remediation data for CVE-2026-90203, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

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.

Sources

NVD record for CVE-2026-90203

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