High 8.2Published May 6, 2026

CVE-2026-43190netfilter: xt_tcpmss: check remaining length before reading optlen

Updated under an hour ago (Oct 28, 2026, 6:50 AM ET)

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Exploited in the last 30 days

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).

CVSS: 8.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Weakness (CWE): CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before f895191dc32c53eaf443b6443fe40945b2f92287; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before cd5beda7e0e32865e214f28034bb92c1cecff885; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before eaedc0bc18be46fe7f58170e967959a932c4f824; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 07a9b32eaae792ff7d0fcac14d8920c937c0a9c3; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 8b300f726640c48c3edfe9c453334dd801f4b74e; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 5e13d0a37666955b6cfddc0f73cb40ed645b8a05; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before f6c412dcfd76b0516d51aa847d8f4c7b70381b09; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 735ee8582da3d239eb0c7a53adca61b79fb228b3	CNA record
linux linux_kernel linux:linux_kernel	from 2.6.12.1 before 5.10.252; from 5.11 before 5.15.202; from 5.16 before 6.1.165; from 6.2 before 6.6.128; from 6.7 before 6.12.75; from 6.13 before 6.18.16; from 6.19 before 6.19.6; 2.6.12; and 5 more ranges	NVD

References

References

https://git.kernel.org/stable/c/f895191dc32c53eaf443b6443fe40945b2f92287	patch
https://git.kernel.org/stable/c/cd5beda7e0e32865e214f28034bb92c1cecff885	patch
https://git.kernel.org/stable/c/eaedc0bc18be46fe7f58170e967959a932c4f824	patch
https://git.kernel.org/stable/c/07a9b32eaae792ff7d0fcac14d8920c937c0a9c3	patch
https://git.kernel.org/stable/c/8b300f726640c48c3edfe9c453334dd801f4b74e	patch
https://git.kernel.org/stable/c/5e13d0a37666955b6cfddc0f73cb40ed645b8a05	patch
https://git.kernel.org/stable/c/f6c412dcfd76b0516d51aa847d8f4c7b70381b09	patch
https://git.kernel.org/stable/c/735ee8582da3d239eb0c7a53adca61b79fb228b3	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.