Critical severity · published Aug 22, 2026
CVE-2026-74597
ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
9.8
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 45% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
e490d1d85cf5e191791979e5f260d32eb4f703a8 before 44fe898df302e91c5ee5acbc71ffa74e78e6c183; e490d1d85cf5e191791979e5f260d32eb4f703a8 before 0dadb0620ab65949a8bc2439dd28ea3c942fe87d; e490d1d85cf5e191791979e5f260d32eb4f703a8 before b6816536a2990c0db44a26130a03e40b441e829b; e490d1d85cf5e191791979e5f260d32eb4f703a8 before 64e41736a26f37ab6215bc2e6df125df05aceb08; e490d1d85cf5e191791979e5f260d32eb4f703a8 before 484134e1eb07d700a73b1e4bbf3fb503e299be60; e490d1d85cf5e191791979e5f260d32eb4f703a8 before 4eb15c465337b18f44716c499cd6ad63eee0ad54; +3 more · source: vendor