CVE-2026-72348
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk14th percentile - higher than 14% of all known CVEs
Summary
In the Linux kernel, the netfilter ip6tables module mishandles malformed IPv6 extension headers. For ah, hbh, and rt matches, the advertised header length checks are missing or outdated. The fix adds the missing check for ah and updates checks for hbh and rt, also setting hotdrop to true to drop malformed packets.
Risk Assessment
Malformed packets with IPv6 extension headers may bypass rules designed to drop them, potentially leading to security policy violations.
Recommendation
Apply the Linux kernel update containing the fix for CVE-2026-72348. Test ip6tables rules regarding extension headers.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop The ah, hbh and rt matches check that the fixed extension header is present, then use the header length field to derive the advertised extension header length for matching. For the ah match, add the missing advertised-length check. For hbh and rt, update the existing advertised-length checks. In all three cases, set hotdrop to true before returning false when the advertised extension header length exceeds the available skb data. Returning false treats the packet as a rule mismatch. Set hotdrop to true and drop malformed packets so they cannot bypass rules intended to drop packets with these IPv6 extension headers.