CVE-2026-64262

CVE CVE-2026-64262EUVD EUVD-2026-48974Published 2026-07-25T08:49:12.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: fuse-uring: end fuse_req on io-uring cancel task work When io_uring delivers task work with tw.cancel set (PF_EXITING, PF_KTHREAD fallback, or percpu_ref_is_dying on the ring context), fuse_uring_send_in_task() takes the cancel branch, assigns -ECANCELED, and falls through to fuse_uring_send(). That path only flips the entry to FRRS_USERSPACE and completes the io_uring cmd; it never discharges the ring entry's owning reference to the fuse_req that fuse_uring_add_req_to_ring_ent() handed it at dispatch time. fuse_uring_send_in_task() tw.cancel == true err = -ECANCELED fuse_uring_send(ent, cmd, err, issue_flags) ent->state = FRRS_USERSPACE list_move(&ent->list, &queue->ent_in_userspace) ent->cmd = NULL io_uring_cmd_done(-ECANCELED) /* ent->fuse_req still set, req still hashed */ The fuse_req stays linked on fpq->processing[hash] and fuse_request_end() is never invoked. The originating syscall thread blocks in D-state in request_wait_answer() until fuse_abort_conn() runs, which can be the entire connection lifetime. For FR_BACKGROUND requests fc->num_background is never decremented either, so repeated cancels inflate the counter until max_background is hit and all later background ops stall. tw.cancel does not imply a connection abort (e.g. a single io_uring worker thread exits while the fuse connection stays up), so this cannot be left for fuse_abort_conn() to clean up. Ending the req but still routing the entry through fuse_uring_send() is not enough: that leaves a req-less entry on ent_in_userspace, and ent_list_request_expired() dereferences ent->fuse_req unconditionally on the head of that list, which would then NULL-deref. Fix the cancel branch to release the entry directly. Remove it from the queue, complete the io_uring cmd, end the fuse_req, free the entry, and drop its queue_refs (waking the teardown waiter if it was the last).

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux c2c9af9a0b13261c36909036057a116f2edb5e1a <bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7; c2c9af9a0b13261c36909036057a116f2edb5e1a <bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd; patch: 6.18.39; patch: 7.2-rc1; 6.14; c2c9af9a0b13261c36909036057a116f2edb5e1a <4f45f276d5b4412eade6f74f2e37f3adba0473ed; patch: 7.1.4; patch: 0

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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