The vulnerability (CVE-2026-74360) in the Linux kernel concerns the handling of exclusive BPF maps (excl_prog_hash). Normally, exclusivity is enforced by check_map_prog_compatibility() to restrict map access to a single program. The bpf_map_elem iterator, however, attaches to the map in bpf_iter_attach_map() without performing this exclusivity check, and it exposes the map's value as a writable buffer. This bypass allows access to exclusive map elements in a way that was not intended, potentially undermining the exclusivity guarantees of these maps. The vulnerability has been resolved in the Linux kernel.

The vulnerability could allow a program to access and modify exclusive BPF map elements that should only be accessible by a single authorized program. This could lead to unauthorized data manipulation within the kernel's BPF subsystem. No known exploits in the wild have been reported. The impact is limited to the integrity and confidentiality of exclusive BPF maps within the kernel.

A fix has been implemented in the Linux kernel to reject exclusive maps for bpf_map_elem iterators, enforcing the exclusivity check properly. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply the official patch.