CVE-2026-74597

ip6_tunnel: clear skb2->cb[] in ip6ip6_err()

State: Published
Severity: 9.8 Critical
Published: Aug 22, 2026
Updated: Oct 16, 2026
Reserved: Aug 15, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 44fe898df302e91c5ee5acbc71ffa74e78e6c183Affected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 0dadb0620ab65949a8bc2439dd28ea3c942fe87dAffected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before b6816536a2990c0db44a26130a03e40b441e829bAffected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 64e41736a26f37ab6215bc2e6df125df05aceb08Affected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 484134e1eb07d700a73b1e4bbf3fb503e299be60Affected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 4eb15c465337b18f44716c499cd6ad63eee0ad54Affected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before fbf40faa0414b753212494ad197542002e66ed9eAffected e490d1d85cf5e191791979e5f260d32eb4f703a8 to before f803c086399da277b5d0ff36a107d0f162751800Affected
LinuxLinux	2.6.22Affected before 2.6.22Not affected 5.10.265 through 5.10.Not affected 5.15.216 through 5.15.Not affected 6.1.183 through 6.1.Not affected 6.6.152 through 6.6.Not affected 6.12.104 through 6.12.Not affected 6.18.45 through 6.18.Not affected 7.1.9 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 44fe898df302e91c5ee5acbc71ffa74e78e6c183Affected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 0dadb0620ab65949a8bc2439dd28ea3c942fe87dAffected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before b6816536a2990c0db44a26130a03e40b441e829bAffected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 64e41736a26f37ab6215bc2e6df125df05aceb08Affected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 484134e1eb07d700a73b1e4bbf3fb503e299be60Affected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before 4eb15c465337b18f44716c499cd6ad63eee0ad54Affected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before fbf40faa0414b753212494ad197542002e66ed9eAffected
e490d1d85cf5e191791979e5f260d32eb4f703a8 to before f803c086399da277b5d0ff36a107d0f162751800Affected

LinuxLinux

2.6.22Affected
before 2.6.22Not affected
5.10.265 through 5.10.*Not affected
5.15.216 through 5.15.*Not affected
6.1.183 through 6.1.*Not affected
6.6.152 through 6.6.*Not affected
6.12.104 through 6.12.*Not affected
6.18.45 through 6.18.*Not affected
7.1.9 through 7.1.*Not affected
7.2 and laterNot affected

References

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