xfrm: fix stale skb->prev after async crypto steals a GSO segment
CVE-2026-68426 · published 10 Aug 2026
How serious is it
- Severity: critical, CVSS score 9.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-68426?
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Who is affected
- Linux Linux: f53c723902d1ac5f0b0a11d7c9dcbff748dde74e to < 4927ab8a8acc8db4fad33e803d1d35e0b16cef83, f53c723902d1ac5f0b0a11d7c9dcbff748dde74e to < b58731e0570bfd3989999fc2baf9ee4fecd5bec6, f53c723902d1ac5f0b0a11d7c9dcbff748dde74e to < 33e1b0d25ca0d2818c635ff80e6aa0d295e08a98, f53c723902d1ac5f0b0a11d7c9dcbff748dde74e to < bbca7cc3b2b4b10afbfee99b81d9ee78f5423046
- Linux Linux: 4.16
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
xfrm: fix stale skb->prev after async crypto steals a GSO segment
skb_gso_segment() leaves the segment list head with ->prev pointing at
the last segment, an invariant validate_xmit_skb_list() relies on when
it sets its tail pointer (tail = skb->prev).
When validate_xmit_xfrm() walks a GSO list and some segments are stolen
by async crypto (->xmit() returns -EINPROGRESS), those segments are
unlinked from the list but the head ->prev is never updated. If the
last segment is the one stolen, the returned head still has ->prev
pointing at it, even though it is now owned by the crypto engine and may
be freed. validate_xmit_skb_list() later does tail->next = skb, writing
through that stale pointer -- a use-after-free.
Repoint skb->prev at the last retained segment before returning.
Check your whole app
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References
- git.kernel.org/stable/c/4927ab8a8acc8db4fad33e803d1d35e0b16cef83
- git.kernel.org/stable/c/b58731e0570bfd3989999fc2baf9ee4fecd5bec6
- git.kernel.org/stable/c/33e1b0d25ca0d2818c635ff80e6aa0d295e08a98
- git.kernel.org/stable/c/bbca7cc3b2b4b10afbfee99b81d9ee78f5423046
- git.kernel.org/stable/c/3f4c3919baf0944ad96580467c302bc6c7758b00
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON