CVE-2026-43190 PUBLISHED

netfilter: xt_tcpmss: check remaining length before reading optlen

Assigner: Linux
Reserved: 01.05.2026 Published: 06.05.2026 Updated: 06.05.2026

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

netfilter: xt_tcpmss: check remaining length before reading optlen

Quoting reporter: In net/netfilter/xt_tcpmss.c (lines 53-68), the TCP option parser reads op[i+1] directly without validating the remaining option length.

If the last byte of the option field is not EOL/NOP (0/1), the code attempts to index op[i+1]. In the case where i + 1 == optlen, this causes an out-of-bounds read, accessing memory past the optlen boundary (either reading beyond the stack buffer _opt or the following payload).

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to f895191dc32c53eaf443b6443fe40945b2f92287 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to cd5beda7e0e32865e214f28034bb92c1cecff885 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to eaedc0bc18be46fe7f58170e967959a932c4f824 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 07a9b32eaae792ff7d0fcac14d8920c937c0a9c3 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 8b300f726640c48c3edfe9c453334dd801f4b74e (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 5e13d0a37666955b6cfddc0f73cb40ed645b8a05 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to f6c412dcfd76b0516d51aa847d8f4c7b70381b09 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 735ee8582da3d239eb0c7a53adca61b79fb228b3 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • unaffected from 5.10.252 to 5.10.* (incl.)
  • unaffected from 5.15.202 to 5.15.* (incl.)
  • unaffected from 6.1.165 to 6.1.* (incl.)
  • unaffected from 6.6.128 to 6.6.* (incl.)
  • unaffected from 6.12.75 to 6.12.* (incl.)
  • unaffected from 6.18.16 to 6.18.* (incl.)
  • unaffected from 6.19.6 to 6.19.* (incl.)
  • unaffected from 7.0 to * (incl.)

References