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CVE-2026-43452: netfilter: x_tables: guard option walkers against 1-byte tail reads

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-08 · updated 2026-10-19
• Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: x_tables: guard option walkers against 1-byte tail reads When the last byte of options is a non-single-byte option kind, walkers that advance with i += op[i + 1] ? : 1 can read op[i + 1] past the end of the option area. Add an explicit i == optlen - 1 check before dereferencing op[i + 1] in xt_tcpudp and xt_dccp option walkers.

Affected products

• Linux kernel: from 2.6.16 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19 — fixed in 5.10.253, 5.15.203, 6.1.167, 6.12.78, 6.18.19, 6.19.9

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.167, 6.12.78. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/5b18b8b35c7cded2d17b2b2604c9b0694ff48d1c
• https://git.kernel.org/stable/c/9b94f0e42ed248eb31929da84ed9f5310d7ff540
• https://git.kernel.org/stable/c/ae1e1267650638136b84c23f2b31250f0ccb6823
• https://git.kernel.org/stable/c/bc18551c6169eac5ed813778d3e3e484002dbbe5
• https://git.kernel.org/stable/c/c2a445367a496a3c25dbc940c10c8bd1cfd4c14a
• https://git.kernel.org/stable/c/c39f84e4be1be63fc60ca7141ea7b76edcea5907
• https://git.kernel.org/stable/c/cfe770220ac2dbd3e104c6b45094037455da81d4
• https://git.kernel.org/stable/c/d04800323336eebf441d153f43234eac9b833d36

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