{"id":"CVE-2025-39977","revision":null,"records":[{"revision":"8148fb2a79104bd5ac4ca09bbf0fea4d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-39977","aliases":[],"title":"futex: Prevent use-after-free during requeue-PI","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Prevent use-after-free during requeue-PI\n\nsyzbot managed to trigger the following race:\n\n T1 T2\n\n futex_wait_requeue_pi()\n futex_do_wait()\n schedule()\n futex_requeue()\n futex_proxy_trylock_atomic()\n futex_requeue_pi_prepare()\n requeue_pi_wake_futex()\n futex_requeue_pi_complete()\n /* preempt */\n\n * timeout/ signal wakes T1 *\n\n futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED\n futex_hash_put()\n // back to userland, on stack futex_q is garbage\n\n /* back */\n wake_up_state(q->task, TASK_NORMAL);\n\nIn this scenario futex_wait_requeue_pi() is able to leave without using\nfutex_q::lock_ptr for synchronization.\n\nThis can be prevented by reading futex_q::task before updating the\nfutex_q::requeue_state. A reference on the task_struct is not needed\nbecause requeue_pi_wake_futex() is invoked with a spinlock_t held which\nimplies a RCU read section.\n\nEven if T1 terminates immediately after, the task_struct will remain valid\nduring T2's wake_up_state(). A READ_ONCE on futex_q::task before\nfutex_requeue_pi_complete() is enough because it ensures that the variable\nis read before the state is updated.\n\nRead futex_q::task before updating the requeue state, use it for the\nfollowing wakeup.","state":0,"publishedAt":"2025-10-15T07:55:58.283+00:00","modifiedAt":"2026-10-15T22:02:35.093+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"kernel/futex/requeue.c\"\n ],\n \"versions\": [\n {\n \"version\": \"07d91ef510fb16a2e0ca7453222105835b7ba3b8\",\n \"lessThan\": \"cb5d19a61274b51b49601214a87af573b43d60fa\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"07d91ef510fb16a2e0ca7453222105835b7ba3b8\",\n \"lessThan\": \"348736955ed6ca6e99ca24b93b1d3fbfe352c181\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"07d91ef510fb16a2e0ca7453222105835b7ba3b8\",\n \"lessThan\": \"a170b9c0dde83312b8b58ccc91509c7c15711641\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"07d91ef510fb16a2e0ca7453222105835b7ba3b8\",\n \"lessThan\": \"d824b2dbdcfe3c390278dd9652ea526168ef6850\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"07d91ef510fb16a2e0ca7453222105835b7ba3b8\",\n \"lessThan\": \"b549113738e8c751b613118032a724b772aa83f2\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"kernel/futex/requeue.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.15\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.15\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.155\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.109\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.50\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.16.10\",\n \"lessThanOrEqual\": \"6.16.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.17\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa","https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181","https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641","https://git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850","https://git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-39977","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-39977","identifiers":["CVE-2025-39977"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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