Bug 2521409 (CVE-2026-74597) - CVE-2026-74597 kernel: ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
Summary: CVE-2026-74597 kernel: ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
Keywords:
Status: NEW
Alias: CVE-2026-74597
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-22 15:44 UTC by OSIDB Bzimport
Modified: 2026-08-24 12:14 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2026-08-22 15:44:11 UTC
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.

Comment 1 Mauro Matteo Cascella 2026-08-24 12:06:43 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082214-CVE-2026-74597-98fc@gregkh/T


Note You need to log in before you can comment on or make changes to this bug.