CVE-2026-90203 PUBLISHED

Squashfs: check block offset is not negative

Assigner: Linux
Reserved: 11.09.2026 Published: 17.09.2026 Updated: 17.09.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to b169185d5c672b989985c6c2e38cafab2548ba88 (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to c2a126fca820ae74872da28de68dc74d4595dc4b (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to 95dadf366c117dcdca78a570e6832071deab1ecd (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to 3d2f0cb66c909ea2312cdef465165bb9a3ba2d84 (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to bbb2218eb072b0a15dc063929200183bd23c2344 (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to d0a3729d464fcf516416a41cf304c0c92126ee03 (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe (excl.)
  • affected from f400e12656ab518be107febfe2315fb1eab5a342 to e300eb5002925b29be803d2661af07266cfa267e (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 2.6.29 is affected
  • unaffected from 0 to 2.6.29 (excl.)
  • unaffected from 5.10.270 to 5.10.* (incl.)
  • unaffected from 5.15.221 to 5.15.* (incl.)
  • unaffected from 6.1.188 to 6.1.* (incl.)
  • unaffected from 6.6.157 to 6.6.* (incl.)
  • unaffected from 6.12.110 to 6.12.* (incl.)
  • unaffected from 6.18.52 to 6.18.* (incl.)
  • unaffected from 7.2.6 to 7.2.* (incl.)
  • unaffected from 7.3-rc1 to * (incl.)

References