{"id":"CVE-2025-39977","title":"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   fute…","summary":"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   fute…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= 07d91ef510fb16a2e0ca7453222105835b7ba3b8 < cb5d19a61274b51b49601214a87af573b43d60fa","Linux >= 07d91ef510fb16a2e0ca7453222105835b7ba3b8 < 348736955ed6ca6e99ca24b93b1d3fbfe352c181","Linux >= 07d91ef510fb16a2e0ca7453222105835b7ba3b8 < a170b9c0dde83312b8b58ccc91509c7c15711641","Linux >= 07d91ef510fb16a2e0ca7453222105835b7ba3b8 < d824b2dbdcfe3c390278dd9652ea526168ef6850","Linux >= 07d91ef510fb16a2e0ca7453222105835b7ba3b8 < b549113738e8c751b613118032a724b772aa83f2","Linux 5.15"],"published":"2025-10-15","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:18:03.763","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-39977","references":[{"url":"https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39977.json"},{"url":"https://access.redhat.com/security/cve/CVE-2025-39977"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2404113"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-39977"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39977"},{"url":"https://lore.kernel.org/linux-cve-announce/2025101558-CVE-2025-39977-b3a2@gregkh/T"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.0015,"epssPercentile":0.04134,"ingestedAt":"2026-09-08T15:33:26.996Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-15T21:55:38.918885Z"},"cwe":["CWE-416"],"scores":{"nvd":7.8,"vendor":4.7},"slug":"CVE-2025-39977","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39977.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}