# CVE-2026-98490: net: openvswitch: conntrack: fix helper UAF due to extensions realloc

> A use-after-free in the Linux kernel Open vSwitch conntrack module allows attackers to execute 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:** 18 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-108815, BELL-CVE-2026-98490, DEBIAN-CVE-2026-98490, GHSA-4r7h-j2g8-7vfx, UBUNTU-CVE-2026-98490

## What is CVE-2026-98490?

CVE-2026-98490 is a critical use after free vulnerability in Linux, published on 18 Oct 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:

net: openvswitch: conntrack: fix helper UAF due to extensions realloc

While calling the helpers, a raw pointer to the extensions area is
wired into expectations list:

  -> nf_ct_helper()
   -> helper->help()
    -> nf_ct_expect_related_report()
     -> nf_ct_expect_insert()
      -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations)

In case the connection is not confirmed yet, more extensions can be
added afterwards with *_ext_add() calls reallocating the extension
space and leaving the now invalid pointer in the expectations list
that is later accessed while removing the expectation.

Make sure that helpers are called at the end after all the other
extensions are already added.

Note that the helper rejection now leaves the mark and labels set,
but that's not different from how the NAT was handled before or how
the mark and the labels were handled on confirmation failure.  And
there are no atomicity guarantees provided by the API anyway.

## Which versions are affected by CVE-2026-98490?


## How do I fix CVE-2026-98490?

Apply the vendor's patch.

## Is CVE-2026-98490 being exploited?

There is no known exploitation of CVE-2026-98490 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98490 and fix it if it is affected.

What it is: CVE-2026-98490 is a critical use after free vulnerability in Linux, published on 18 Oct 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-2026-98490 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-2026-98490/ (Markdown: https://insights.sbomify.com/CVE-2026-98490/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98490
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98490
- OSV: https://osv.dev/vulnerability/CVE-2026-98490

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98490/
Summaries are generated and may contain mistakes; the official description above is the record.