{"cve":"CVE-2026-80776","nvd":{"published":"2026-09-04T16:18:03.250","modified":"2026-09-04T16:18:03.250","status":"Received","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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/19b4be0717fa83265d66aea836b7022d898422cf","https://git.kernel.org/stable/c/4a7e941ca29a608c6244cbd028d3599ecaef7207","https://git.kernel.org/stable/c/8e7ff730dd96519a333d1570edf1c3fabb6d3629"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:52:03.409947763+00:00"},"epss":{"cve":"CVE-2026-80776","score":0.00166,"percentile":0.05844,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}