CVE-2026-74669: ipvs: clear IPv4 options after rebasing tunnel ICMP errors
In the Linux kernel, the following vulnerability has been resolved:
ipvs: clear IPv4 options after rebasing tunnel ICMP errors
ipvsinicmp() rebases an skb from the outer ICMP packet to the quoted original request before passing it to icmpsend(). However, IPCB(skb)->opt still describes the outer IPv4 header.
A timestamp option in the outer header can therefore leave an offset that points into the quoted transport header after the rebase. ipoptionsecho() treats a byte at that stale location as the option length and copies it into the fixed-size option storage on the icmpsend() stack, causing a stack out-of-bounds write.
Clear the stale option metadata after resetting the network header. Keep the remaining control block fields, including the ingress interface used by the ICMP response path.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Operational
Clear stale IPv4 option metadata after resetting/rebasing the network header so that IPCB(skb)->opt no longer describes the outer IPv4 header (stale location after rebase can be misinterpreted by __ip_options_echo() in the ICMP response path).