# CVE-2026-97611: net: openvswitch: fix use-after-free of the flow table mask array

> A use-after-free in the Linux kernel Open vSwitch flow table allows attackers to cause denial of service or execute arbitrary code.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104708, BELL-CVE-2026-97611, DEBIAN-CVE-2026-97611, GHSA-p256-hqvm-38xq, UBUNTU-CVE-2026-97611

## What is CVE-2026-97611?

CVE-2026-97611 is a high-severity use after free vulnerability in Linux, published on 25 Sep 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:

net: openvswitch: fix use-after-free of the flow table mask array

tbl_mask_array_realloc() retires the old mask_array before it stops being
reachable:

	old = ovsl_dereference(tbl->mask_array);
	if (old) {
		...
		call_rcu(&old->rcu, mask_array_rcu_cb);
	}

	rcu_assign_pointer(tbl->mask_array, new);

call_rcu() only waits for read-side critical sections already in flight.
tbl->mask_array still points at old between the call_rcu() and the
rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in
that window picks up old in a fresh critical section that the pending
grace period does not cover.

tbl_mask_array_realloc() runs in process context under ovs_mutex, so the
window is preemptible and can outlast the grace period. Then
mask_array_rcu_cb() frees old before the swap runs:

  BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0
  Read of size 8 at addr ffff888020b3e018 by task poc/741
   flow_lookup.constprop.0+0x2bf/0x2f0
   ovs_flow_tbl_lookup_stats+0x4a3/0x5c0
   ovs_dp_process_packet+0x19c/0x710
   ovs_vport_receive+0x243/0x390
   internal_dev_xmit+0x81/0x170
  Freed by task 728:
   kfree+0x16a/0x4e0
   rcu_core+0x853/0x1030

Publish the new array before retiring the old one. The kfree_rcu() that
call_rcu() replaced ran after the swap.

## Which versions are affected by CVE-2026-97611?


## How do I fix CVE-2026-97611?

Apply the vendor's patch.

## Is CVE-2026-97611 being exploited?

There is no known exploitation of CVE-2026-97611 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97611 and fix it if it is affected.

What it is: CVE-2026-97611 is a high-severity use after free vulnerability in Linux, published on 25 Sep 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-2026-97611 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-2026-97611/ (Markdown: https://insights.sbomify.com/CVE-2026-97611/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97611
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97611
- OSV: https://osv.dev/vulnerability/CVE-2026-97611

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97611/
Summaries are generated and may contain mistakes; the official description above is the record.