# CVE-2026-98230: xfrm: use hlist_del_init_rcu for state_cache and state_cache_input

> A use-after-free vulnerability in the Linux kernel's xfrm subsystem allows attackers to execute arbitrary code or escalate privileges via double deletion of state cache nodes.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98230, DEBIAN-CVE-2026-98230, GHSA-3cj7-gr4r-g9gh, UBUNTU-CVE-2026-98230

## What is CVE-2026-98230?

CVE-2026-98230 is a high-severity use after free vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

xfrm: use hlist_del_init_rcu for state_cache and state_cache_input

Commit 14acf9652e56 ("xfrm: defensively unhash xfrm_state lists in
__xfrm_state_delete") converted bydst/bysrc/byseq/byspi from
hlist_del_rcu() to hlist_del_init_rcu() so that a second
__xfrm_state_delete() on the same object becomes a no-op rather than a
write through LIST_POISON pprev. It missed state_cache and
state_cache_input, which kept hlist_del_rcu():

- hlist_del_rcu() leaves pprev = LIST_POISON2 (non-NULL), so
  hlist_unhashed() returns false.
- hlist_del_init_rcu() leaves pprev = NULL, so hlist_unhashed()
  returns true.

A second __xfrm_state_delete() therefore enters __hlist_del() on the
already-deleted state_cache/state_cache_input nodes and does
WRITE_ONCE(*pprev, next) through LIST_POISON2 — a write use-after-free
once the slab is reused. The corruption can in turn cause a subsequent
hlist_for_each_entry_rcu traversal to follow a dangling next pointer,
producing the read use-after-free reported in xfrm_input_state_lookup().

Switch state_cache and state_cache_input to hlist_del_init_rcu() to
match the other four lists, closing the write use-after-free and, with
it, the read use-after-free it spawns.

## Which versions are affected by CVE-2026-98230?


## How do I fix CVE-2026-98230?

Apply the vendor's patch.

## Is CVE-2026-98230 being exploited?

There is no known exploitation of CVE-2026-98230 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98230 and fix it if it is affected.

What it is: CVE-2026-98230 is a high-severity use after free vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98230 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-2026-98230/ (Markdown: https://insights.sbomify.com/CVE-2026-98230/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98230
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98230
- OSV: https://osv.dev/vulnerability/CVE-2026-98230

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98230/
Summaries are generated and may contain mistakes; the official description above is the record.