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CVE-2026-43190 is an out-of-bounds read vulnerability in the Linux kernel netfilter xt_tcpmss component, in net/netfilter/xt_tcpmss.c. The flaw is caused by the TCP option parser reading the option length byte at op[i+1] without first verifying that sufficient option data remains. If the final byte of the TCP option area is neither EOL nor NOP, the parser can attempt to access op[i+1] when i + 1 equals optlen, resulting in a read past the end of the TCP option boundary. Depending on layout, the read can extend beyond the local option buffer or into adjacent packet data. The issue was fixed by adding a remaining-length check before reading optlen.
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24 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel netfilter xt_tcpmss vulnerability caused by not checking remaining length before reading optlen.
A Linux kernel netfilter xt_tcpmss vulnerability involving insufficient length checking before reading TCP option length.
A Linux kernel vulnerability in netfilter xt_tcpmss involving insufficient remaining-length checks before reading optlen.
Linux kernel netfilter xt_tcpmss vulnerability involving bounds checking before reading optlen.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.