CVE-2026-90393 in Linux
Riassunto
di MITRE • 17/09/2026
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix potential UAF in bpf_netns_link_update_prog
In bpf_netns_link_update_prog, the checks for old_prog and prog type are currently performed locklessly before acquiring netns_bpf_mutex. This creates a race condition that can lead to a UAF issue.
If two threads concurrently execute BPF_LINK_UPDATE on the same netns link, the following execution path can trigger a UAF:
CPU0 CPU1 bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) return -EPERM; bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) ... old_prog = xchg(&link->prog, new_prog); bpf_prog_put(old_prog); if (new_prog->type != link->prog->type) <-- trigger UAF
Fix this by moving the old_prog and prog->type checks inside the netns_bpf_mutex critical section. Meanwhile, use guard() to simplify lock management and avoid all the goto jumping.
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