Batman‑adv, a MAC‑level virtual network overlay in the Linux kernel, has a flaw in its fragmentation logic that allows an attacker to embed a BATADV_UNICAST_FRAG packet inside the reassembled payload of another BATADV_UNICAST_FRAG packet. This matryoshka‑style nesting causes the kernel to recursively process the packet over and over until the kernel stack is exhausted, leading to a crash or reboot of the host and disruption of all network services.

All Linux kernels that include the batman‑adv overlay module may be affected. No specific kernel versions were listed in the advisory; thus any kernel prior to the commit that removed this unbounded recursion can be vulnerable.

The defect requires an attacker to send crafted BATADV packets over the network, so a remote attacker with connectivity to the target host can trigger it. While no CVSS or EPSS score is available, the potential for a stack‑overflow denial of service makes the vulnerability high impact. It is not listed in the CISA KEV catalog, but should be addressed promptly to prevent service disruption.