# 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.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-95039, BELL-CVE-2026-68426, DEBIAN-CVE-2026-68426, GHSA-g9mw-m3g9-8x3m, UBUNTU-CVE-2026-68426

## 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 (Use After Free)

## Which versions are affected by CVE-2026-68426?


## How do I fix CVE-2026-68426?

Apply the vendor's patch.

## Is CVE-2026-68426 being exploited?

There is no known exploitation of CVE-2026-68426 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68426 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-68426 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68426/ (Markdown: https://insights.sbomify.com/CVE-2026-68426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68426
- OSV: https://osv.dev/vulnerability/CVE-2026-68426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68426/
Summaries are generated and may contain mistakes; the official description above is the record.