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.
- 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
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 include Linux kernel.
How do I fix CVE-2026-52916?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
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
Sources
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 and 3 more.