{"id":"CVE-2026-74471","state":"PUBLISHED","title":"tracing: Check return value of __register_event() in trace_module_add_events()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Check return value of __register_event() in trace_module_add_events()\n\ntrace_module_add_events() ignores the return value of __register_event()\nand unconditionally calls __add_event_to_tracers() for each event.\n\nIf __register_event() fails (for example, if event_init() fails), the\ntrace_event_call is not added to ftrace_events list, but\n__add_event_to_tracers() still creates a trace_event_file pointing to it.\nIf module loading subsequently fails and module memory is freed, tracing\nstate retains a stale trace_event_call pointer in trace_event_file,\nleading to a use-after-free when tracefs or tracing subsystem operations\nare later executed.\n\nFix this by checking the return value of __register_event() and only\ncalling __add_event_to_tracers() if event registration succeeded.","publishedAt":"2026-08-15T12:27:08.128Z","updatedAt":"2026-10-16T19:05:47.824Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"3bf965a2827c44f03294107703e7ba53fbd0a69a","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"9d6d79744f01eacaf3d5522f4fcd59939581abfd","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"54b7a358f6399c1242d2fb7f4f96085af34baa5e","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"d61ee2a27dfd5eb43ddc18af40168f5b9eb1cea5","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"22f954f7a8afe975e85517aff41b35defe05144b","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"cbb5ed3be9cae70e1c12b1991009b4e12bf4a4ca","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"000765dcdc3edf128990762790543adc4b868f6c","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"ac8719969e6c3c54e939834df812bc41f25453cf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.10","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]}],"references":["https://git.kernel.org/stable/c/3bf965a2827c44f03294107703e7ba53fbd0a69a","https://git.kernel.org/stable/c/9d6d79744f01eacaf3d5522f4fcd59939581abfd","https://git.kernel.org/stable/c/54b7a358f6399c1242d2fb7f4f96085af34baa5e","https://git.kernel.org/stable/c/d61ee2a27dfd5eb43ddc18af40168f5b9eb1cea5","https://git.kernel.org/stable/c/22f954f7a8afe975e85517aff41b35defe05144b","https://git.kernel.org/stable/c/cbb5ed3be9cae70e1c12b1991009b4e12bf4a4ca","https://git.kernel.org/stable/c/000765dcdc3edf128990762790543adc4b868f6c","https://git.kernel.org/stable/c/ac8719969e6c3c54e939834df812bc41f25453cf"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74471.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74471","state":"PUBLISHED","datePublished":"2026-08-15T12:27:08.128Z","dateUpdated":"2026-10-16T19:05:47.824Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.902Z"},"containers":{"cna":{"title":"tracing: Check return value of __register_event() in trace_module_add_events()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Check return value of __register_event() in trace_module_add_events()\n\ntrace_module_add_events() ignores the return value of __register_event()\nand unconditionally calls __add_event_to_tracers() for each event.\n\nIf __register_event() fails (for example, if event_init() fails), the\ntrace_event_call is not added to ftrace_events list, but\n__add_event_to_tracers() still creates a trace_event_file pointing to it.\nIf module loading subsequently fails and module memory is freed, tracing\nstate retains a stale trace_event_call pointer in trace_event_file,\nleading to a use-after-free when tracefs or tracing subsystem operations\nare later executed.\n\nFix this by checking the return value of __register_event() and only\ncalling __add_event_to_tracers() if event registration succeeded."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"3bf965a2827c44f03294107703e7ba53fbd0a69a","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"9d6d79744f01eacaf3d5522f4fcd59939581abfd","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"54b7a358f6399c1242d2fb7f4f96085af34baa5e","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"d61ee2a27dfd5eb43ddc18af40168f5b9eb1cea5","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"22f954f7a8afe975e85517aff41b35defe05144b","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"cbb5ed3be9cae70e1c12b1991009b4e12bf4a4ca","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"000765dcdc3edf128990762790543adc4b868f6c","versionType":"git"},{"version":"ae63b31e4d0e2ec09c569306ea46f664508ef717","status":"affected","lessThan":"ac8719969e6c3c54e939834df812bc41f25453cf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.10","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3bf965a2827c44f03294107703e7ba53fbd0a69a"},{"url":"https://git.kernel.org/stable/c/9d6d79744f01eacaf3d5522f4fcd59939581abfd"},{"url":"https://git.kernel.org/stable/c/54b7a358f6399c1242d2fb7f4f96085af34baa5e"},{"url":"https://git.kernel.org/stable/c/d61ee2a27dfd5eb43ddc18af40168f5b9eb1cea5"},{"url":"https://git.kernel.org/stable/c/22f954f7a8afe975e85517aff41b35defe05144b"},{"url":"https://git.kernel.org/stable/c/cbb5ed3be9cae70e1c12b1991009b4e12bf4a4ca"},{"url":"https://git.kernel.org/stable/c/000765dcdc3edf128990762790543adc4b868f6c"},{"url":"https://git.kernel.org/stable/c/ac8719969e6c3c54e939834df812bc41f25453cf"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only via local init_module/finit_module module loading (MODULE_STATE_COMING notifier) and subsequent tracefs/tracing operations on poisoned event files; there is no network, adjacent-wireless, or physical-device input path into trace_module_add_events() or the stale trace_event_file dereferences.\nAC:L - An attacker can deterministically craft a module whose trace events fail event_init()/__register_event() while __add_event_to_tracers() still runs, then force module-load failure or rmmod to free module memory; no uncontrollable race, rare kernel config, or victim-specific memory layout is required.\nPR:L - Triggering the UAF requires only local tracefs/tracing access, which tracing_check_open() gates solely with LOCKDOWN_TRACEFS and DAC (no capable() check), commonly granted to tracing-group/Android/ChromeOS diagnostics users; priming stale pointers via init_module uses capable(CAP_SYS_MODULE) but is achievable on permissive dev/container hosts loading attacker modules.\nUI:N - Once tracefs is accessible, the attacker can read/write event enable/format files or invoke tracing helpers that iterate tr->events and dereference the stale trace_event_call without any separate victim user performing mounts, clicks, or configuration changes.\nS:U - The use-after-free corrupts kernel tracing heap/metadata within the same OS security authority and enables local privilege escalation; it does not cross VM, container, IOMMU, or hardware trust boundaries.\nC:H - Stale trace_event_file->event_call pointers reference freed module slab memory; subsequent trace_event_name(), call->class, and reg/unreg callbacks read attacker-influenced reclaimed heap contents, giving an arbitrary kernel memory read primitive typical of UAF bugs.\nI:H - Operations such as __ftrace_event_enable_disable() invoke call->class->reg() through the dangling trace_event_call and manipulate event flags/filters on reclaimed objects, providing controllable kernel writes and a standard UAF path to code execution.\nA:H - Dereferencing freed module-resident trace_event_call structures from tracefs or tracing subsystem operations readily causes kernel oops/panic; even without full exploitation, the UAF reliably threatens system availability and can be retriggered at 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