{"api_version":"1","generated_at":"2026-08-02T13:38:15+00:00","cve":"CVE-2026-64262","urls":{"html":"https://cve.report/CVE-2026-64262","api":"https://cve.report/api/cve/CVE-2026-64262.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64262","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64262"},"summary":{"title":"fuse-uring: end fuse_req on io-uring cancel task work","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: end fuse_req on io-uring cancel task work\n\nWhen io_uring delivers task work with tw.cancel set (PF_EXITING,\nPF_KTHREAD fallback, or percpu_ref_is_dying on the ring context),\nfuse_uring_send_in_task() takes the cancel branch, assigns\n-ECANCELED, and falls through to fuse_uring_send(). That path only\nflips the entry to FRRS_USERSPACE and completes the io_uring cmd;\nit never discharges the ring entry's owning reference to the\nfuse_req that fuse_uring_add_req_to_ring_ent() handed it at\ndispatch time.\n\n    fuse_uring_send_in_task()\n      tw.cancel == true\n        err = -ECANCELED\n      fuse_uring_send(ent, cmd, err, issue_flags)\n        ent->state = FRRS_USERSPACE\n        list_move(&ent->list, &queue->ent_in_userspace)\n        ent->cmd = NULL\n        io_uring_cmd_done(-ECANCELED)\n        /* ent->fuse_req still set, req still hashed */\n\nThe fuse_req stays linked on fpq->processing[hash] and\nfuse_request_end() is never invoked. The originating syscall\nthread blocks in D-state in request_wait_answer() until\nfuse_abort_conn() runs, which can be the entire connection\nlifetime. For FR_BACKGROUND requests fc->num_background is never\ndecremented either, so repeated cancels inflate the counter until\nmax_background is hit and all later background ops stall. tw.cancel does\nnot imply a connection abort (e.g. a single io_uring worker thread exits\nwhile the fuse connection stays up), so this cannot be left for\nfuse_abort_conn() to clean up.\n\nEnding the req but still routing the entry through fuse_uring_send()\nis not enough: that leaves a req-less entry on ent_in_userspace, and\nent_list_request_expired() dereferences ent->fuse_req unconditionally\non the head of that list, which would then NULL-deref.\n\nFix the cancel branch to release the entry directly. Remove it from the\nqueue, complete the io_uring cmd, end the fuse_req, free the entry, and\ndrop its queue_refs (waking the teardown waiter if it was the last).","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:06","updated_at":"2026-07-30 15:00:27"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7","name":"https://git.kernel.org/stable/c/bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd","name":"https://git.kernel.org/stable/c/bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4f45f276d5b4412eade6f74f2e37f3adba0473ed","name":"https://git.kernel.org/stable/c/4f45f276d5b4412eade6f74f2e37f3adba0473ed","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64262","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64262","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c2c9af9a0b13261c36909036057a116f2edb5e1a bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c2c9af9a0b13261c36909036057a116f2edb5e1a 4f45f276d5b4412eade6f74f2e37f3adba0473ed git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c2c9af9a0b13261c36909036057a116f2edb5e1a bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.14","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.39 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.4 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64262","cve":"CVE-2026-64262","epss":"0.001980000","percentile":"0.098420000","score_date":"2026-08-01","updated_at":"2026-08-02 00:11:13"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/fuse/dev_uring.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7","status":"affected","version":"c2c9af9a0b13261c36909036057a116f2edb5e1a","versionType":"git"},{"lessThan":"4f45f276d5b4412eade6f74f2e37f3adba0473ed","status":"affected","version":"c2c9af9a0b13261c36909036057a116f2edb5e1a","versionType":"git"},{"lessThan":"bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd","status":"affected","version":"c2c9af9a0b13261c36909036057a116f2edb5e1a","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/fuse/dev_uring.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.14"},{"lessThan":"6.14","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.39","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.39","versionStartIncluding":"6.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.4","versionStartIncluding":"6.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc1","versionStartIncluding":"6.14","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: end fuse_req on io-uring cancel task work\n\nWhen io_uring delivers task work with tw.cancel set (PF_EXITING,\nPF_KTHREAD fallback, or percpu_ref_is_dying on the ring context),\nfuse_uring_send_in_task() takes the cancel branch, assigns\n-ECANCELED, and falls through to fuse_uring_send(). That path only\nflips the entry to FRRS_USERSPACE and completes the io_uring cmd;\nit never discharges the ring entry's owning reference to the\nfuse_req that fuse_uring_add_req_to_ring_ent() handed it at\ndispatch time.\n\n    fuse_uring_send_in_task()\n      tw.cancel == true\n        err = -ECANCELED\n      fuse_uring_send(ent, cmd, err, issue_flags)\n        ent->state = FRRS_USERSPACE\n        list_move(&ent->list, &queue->ent_in_userspace)\n        ent->cmd = NULL\n        io_uring_cmd_done(-ECANCELED)\n        /* ent->fuse_req still set, req still hashed */\n\nThe fuse_req stays linked on fpq->processing[hash] and\nfuse_request_end() is never invoked. The originating syscall\nthread blocks in D-state in request_wait_answer() until\nfuse_abort_conn() runs, which can be the entire connection\nlifetime. For FR_BACKGROUND requests fc->num_background is never\ndecremented either, so repeated cancels inflate the counter until\nmax_background is hit and all later background ops stall. tw.cancel does\nnot imply a connection abort (e.g. a single io_uring worker thread exits\nwhile the fuse connection stays up), so this cannot be left for\nfuse_abort_conn() to clean up.\n\nEnding the req but still routing the entry through fuse_uring_send()\nis not enough: that leaves a req-less entry on ent_in_userspace, and\nent_list_request_expired() dereferences ent->fuse_req unconditionally\non the head of that list, which would then NULL-deref.\n\nFix the cancel branch to release the entry directly. Remove it from the\nqueue, complete the io_uring cmd, end the fuse_req, free the entry, and\ndrop its queue_refs (waking the teardown waiter if it was the last)."}],"providerMetadata":{"dateUpdated":"2026-07-25T08:49:12.599Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7"},{"url":"https://git.kernel.org/stable/c/4f45f276d5b4412eade6f74f2e37f3adba0473ed"},{"url":"https://git.kernel.org/stable/c/bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd"}],"title":"fuse-uring: end fuse_req on io-uring cancel task work","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64262","datePublished":"2026-07-25T08:49:12.599Z","dateReserved":"2026-07-19T15:36:31.774Z","dateUpdated":"2026-07-25T08:49:12.599Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:06","lastModifiedDate":"2026-07-30 15:00:27","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64262","Ordinal":"1","Title":"fuse-uring: end fuse_req on io-uring cancel task work","CVE":"CVE-2026-64262","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64262","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: end fuse_req on io-uring cancel task work\n\nWhen io_uring delivers task work with tw.cancel set (PF_EXITING,\nPF_KTHREAD fallback, or percpu_ref_is_dying on the ring context),\nfuse_uring_send_in_task() takes the cancel branch, assigns\n-ECANCELED, and falls through to fuse_uring_send(). That path only\nflips the entry to FRRS_USERSPACE and completes the io_uring cmd;\nit never discharges the ring entry's owning reference to the\nfuse_req that fuse_uring_add_req_to_ring_ent() handed it at\ndispatch time.\n\n    fuse_uring_send_in_task()\n      tw.cancel == true\n        err = -ECANCELED\n      fuse_uring_send(ent, cmd, err, issue_flags)\n        ent->state = FRRS_USERSPACE\n        list_move(&ent->list, &queue->ent_in_userspace)\n        ent->cmd = NULL\n        io_uring_cmd_done(-ECANCELED)\n        /* ent->fuse_req still set, req still hashed */\n\nThe fuse_req stays linked on fpq->processing[hash] and\nfuse_request_end() is never invoked. The originating syscall\nthread blocks in D-state in request_wait_answer() until\nfuse_abort_conn() runs, which can be the entire connection\nlifetime. For FR_BACKGROUND requests fc->num_background is never\ndecremented either, so repeated cancels inflate the counter until\nmax_background is hit and all later background ops stall. tw.cancel does\nnot imply a connection abort (e.g. a single io_uring worker thread exits\nwhile the fuse connection stays up), so this cannot be left for\nfuse_abort_conn() to clean up.\n\nEnding the req but still routing the entry through fuse_uring_send()\nis not enough: that leaves a req-less entry on ent_in_userspace, and\nent_list_request_expired() dereferences ent->fuse_req unconditionally\non the head of that list, which would then NULL-deref.\n\nFix the cancel branch to release the entry directly. Remove it from the\nqueue, complete the io_uring cmd, end the fuse_req, free the entry, and\ndrop its queue_refs (waking the teardown waiter if it was the last).","Type":"Description","Title":"fuse-uring: end fuse_req on io-uring cancel task work"}]}}}