CVE-2026-68426 xfrm: fix stale skb->prev after async crypto steals a GSO segment
A use-after-free in the Linux kernel xfrm subsystem allows attackers to execute arbitrary code or escalate privileges via crafted network packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68426?
CVE-2026-68426 is a critical use after free vulnerability in Linux, published on 10 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-68426?
How do I fix CVE-2026-68426?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-68426 being exploited?
There is no known exploitation of CVE-2026-68426 in the wild and no public exploit code.
Sources
Also known as AZL-95039, BELL-CVE-2026-68426, DEBIAN-CVE-2026-68426, GHSA-g9mw-m3g9-8x3m, UBUNTU-CVE-2026-68426.