{"id":"CVE-2026-80776","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-80776","generatedAt":"2026-10-28T09:26:33.696Z","title":"In the Linux kernel, the following vulnerability has been resolved: futex: Fix race in futex_pivot_pending() during private hash resize A task performing a custom private hash resize can remain blocked in uninterruptible sleep indefinitely.","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Fix race in futex_pivot_pending() during private hash resize\n\nA task performing a custom private hash resize can remain blocked in\nuninterruptible sleep indefinitely.  The hung-task detector reports:\n\n  INFO: task futex-resizer:314 blocked for more than 10 seconds.\n  task:futex-resizer state:D stack:14824 pid:314 tgid:312 ppid:311\n\n  Call Trace:\n   __schedule+0x521/0xf30\n   schedule+0x22/0xa0\n   futex_hash_allocate+0x3db/0x490\n   __do_sys_prctl+0x6f5/0xbd0\n   do_syscall_64+0xf9/0x530\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n  Kernel panic - not syncing: hung_task: blocked tasks\n\nfutex_pivot_pending() allows the resize request to continue when\neither no replacement hash is pending (hash_new == NULL) or the current\nhash reference count has reached zero.\n\nAfter the final-reference wake, another futex task can complete the\npivot between the two observations:\n\n  T1                                  T2\n\n  futex_hash_allocate()\n    wait_var_event(mm, ...)\n      futex_pivot_pending(mm)\n        hash_new != NULL\n                                      futex_hash()\n                                        futex_ref_get(old) -> false\n                                        futex_pivot_hash(mm)\n                                          hash_new = NULL\n                                          __futex_pivot_hash(mm, new)\n                                            rcu_assign_pointer(hash, new)\n        fph = rcu_dereference(hash) /* new */\n        futex_ref_is_dead(fph) -> false\n      schedule()\n\nThe pivot changes the state from hash_new != NULL with a dead current\nhash to hash_new == NULL with a live current hash.  Because\nfutex_pivot_pending() reads hash_new and hash without serialization,\nthe resize task can observe hash_new in the pre-pivot state and hash in\nthe post-pivot state, causing futex_pivot_pending() to return false even\nthough the pivot has completed.  The task then goes to sleep after the\nwakeup has already been consumed.\n\nSerialize state reads in futex_pivot_pending() using futex_mm_phash::lock.\nThis guarantees that futex_pivot_pending() observes hash_new and hash\natomically, eliminating the race condition.","published":"2026-09-04T16:18:03.000Z","lastModified":"2026-09-04T16:18:03.000Z","status":"Received","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":null,"cwe":[],"affected":[],"epss":{"score":0.00166,"percentile":0.05792,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"unknown","text":"Not yet scored. NVD analysis is pending; check back once CVSS and EPSS values are published."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/19b4be0717fa83265d66aea836b7022d898422cf","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4a7e941ca29a608c6244cbd028d3599ecaef7207","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8e7ff730dd96519a333d1570edf1c3fabb6d3629","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80776","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}