# CVE-2026-52916: batman-adv: frag: disallow unicast fragment in fragment

> A malicious sender can cause a kernel stack exhaustion denial of service in the batman-adv module by sending nested unicast fragment packets.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** AZL-90282, BELL-CVE-2026-52916, DEBIAN-CVE-2026-52916, GHSA-7cg4-79f4-7w2g, ROOT-OS-DEBIAN-11-CVE-2026-52916, ROOT-OS-DEBIAN-12-CVE-2026-52916, ROOT-OS-UBUNTU-2204-CVE-2026-52916, ROOT-OS-UBUNTU-2404-CVE-2026-52916, UBUNTU-CVE-2026-52916

## What is CVE-2026-52916?

CVE-2026-52916 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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:

batman-adv: frag: disallow unicast fragment in fragment

batadv_frag_skb_buffer() is called by batadv_batman_skb_recv() when a
BATADV_UNICAST_FRAG packet is received. Once all fragments are collected
and the packet is reassembled, batadv_recv_frag_packet() calls
batadv_batman_skb_recv() again to process the defragmented payload.

A malicious sender can craft a BATADV_UNICAST_FRAG packet whose reassembled
payload is itself a BATADV_UNICAST_FRAG packet (matryoshka-style nesting).
Each nesting level recurses through batadv_batman_skb_recv() without bound,
growing the kernel stack until it is exhausted.

Since refragmentation or fragments in fragments are not actually allowed,
discard all packets which are still BATADV_UNICAST_FRAG packets after the
defragmentation process.

## Which versions are affected by CVE-2026-52916?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52916?

Apply the vendor's patch.

## Is CVE-2026-52916 being exploited?

There is no known exploitation of CVE-2026-52916 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52916 and fix it if it is affected.

What it is: CVE-2026-52916 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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-2026-52916 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-52916/ (Markdown: https://insights.sbomify.com/CVE-2026-52916/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52916
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52916
- OSV: https://osv.dev/vulnerability/CVE-2026-52916

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52916/
Summaries are generated and may contain mistakes; the official description above is the record.