CVE-2026-74597 (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: ip6_tunnel: clear skb2->cb[] in ip6ip6_err() ip6ip6_err() clones an outer IPv6 ICMP error skb, pulls it to the quoted inner IPv6 packet, and then passes the clone to icmpv6_send(). The clone still carries the outer packet's inet6_skb_parm in skb->cb. If the outer packet had a Home Address Option, IP6CB(skb2)->dsthao remains non-zero after skb_pull(). icmpv6_send() later calls mip6_addr_swap(), which uses that stale dsthao offset against the quoted inner packet. A malformed inner destination-options header can then make the HAO lookup and address swap run past the end of the quoted packet and corrupt skb_shared_info. Clear skb2->cb[] before pulling the quoted inner IPv6 packet so the reply path does not reuse metadata left by the outer IPv6 stack.

Is your site exposed to CVE-2026-74597?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0051

Probability of exploitation

0.43%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/0dadb0620ab65949a8bc2439dd28ea3c942fe87d https://git.kernel.org/stable/c/44fe898df302e91c5ee5acbc71ffa74e78e6c183 https://git.kernel.org/stable/c/484134e1eb07d700a73b1e4bbf3fb503e299be60 https://git.kernel.org/stable/c/4eb15c465337b18f44716c499cd6ad63eee0ad54 https://git.kernel.org/stable/c/64e41736a26f37ab6215bc2e6df125df05aceb08 https://git.kernel.org/stable/c/b6816536a2990c0db44a26130a03e40b441e829b https://git.kernel.org/stable/c/f803c086399da277b5d0ff36a107d0f162751800 https://git.kernel.org/stable/c/fbf40faa0414b753212494ad197542002e66ed9e

Frequently Asked Questions

What is CVE-2026-74597? +

In the Linux kernel, the following vulnerability has been resolved: ip6_tunnel: clear skb2->cb[] in ip6ip6_err() ip6ip6_err() clones an outer IPv6 ICMP error skb, pulls it to the quoted inner IPv6 packet, and then passes the clone to icmpv6_send(). The clone still carries the outer packet's inet6_skb_parm in skb->cb. If the outer packet had a Home Address Option, IP6CB(skb2)->dsthao remains non-zero after skb_pull(). icmpv6_send() later calls mip6_addr_swap(), which uses that stale dsthao offset against the quoted inner packet. A malformed inner destination-options header can then make the HAO lookup and address swap run past the end of the quoted packet and corrupt skb_shared_info. Clear skb2->cb[] before pulling the quoted inner IPv6 packet so the reply path does not reuse metadata left by the outer IPv6 stack. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-74597? +

CVE-2026-74597 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0051, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-74597? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-74597