CVE-2026-80875: ipvs: use parsed transport offset in TCP state lookup
In the Linux kernel, the following vulnerability has been resolved:
ipvs: use parsed transport offset in TCP state lookup
TCP state handling reparses the skb to find the TCP header. For IPv6 it uses sizeof(struct ipv6hdr), while the surrounding IPVS code already parsed the packet with ipvsfilliphskb() and has the real transport-header offset in iph.len.
This makes TCP state handling look at the wrong bytes when an IPv6 packet carries extension headers. Use the parsed transport offset passed down from ipvssetstate() when reading the TCP header.
For IPv4 and for IPv6 packets without extension headers, the passed offset matches the previous value.
Affected Software
Event History
Frequently Asked Questions
Which traffic is affected by this issue?
The issue affects IPVS TCP state handling for IPv6 packets that include extension headers. IPv4 traffic and IPv6 traffic without extension headers use the same transport offset as before.
What must an attacker be able to send to trigger the incorrect TCP-header lookup?
An attacker would need to cause IPVS to process TCP traffic carried in IPv6 packets with extension headers. The provided information does not state any additional authentication or access requirements.
How can I determine whether my deployment is exposed?
Review whether the system uses IPVS and handles IPv6 TCP traffic that may contain IPv6 extension headers. Systems limited to IPv4, or to IPv6 TCP packets without extension headers, are not described as affected by the incorrect offset calculation.