CVE-2026-52916

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> batman-adv: frag: disallow unicast fragment in fragment<br /> <br /> batadv_frag_skb_buffer() is called by batadv_batman_skb_recv() when a<br /> BATADV_UNICAST_FRAG packet is received. Once all fragments are collected<br /> and the packet is reassembled, batadv_recv_frag_packet() calls<br /> batadv_batman_skb_recv() again to process the defragmented payload.<br /> <br /> A malicious sender can craft a BATADV_UNICAST_FRAG packet whose reassembled<br /> payload is itself a BATADV_UNICAST_FRAG packet (matryoshka-style nesting).<br /> Each nesting level recurses through batadv_batman_skb_recv() without bound,<br /> growing the kernel stack until it is exhausted.<br /> <br /> Since refragmentation or fragments in fragments are not actually allowed,<br /> discard all packets which are still BATADV_UNICAST_FRAG packets after the<br /> defragmentation process.