{
  "affected": [
    {
      "ranges": [
        {
          "events": [
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              "introduced": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba"
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              "fixed": "92e47ad03e03dbb5515bdf06444bf6b1e147310d"
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            {
              "fixed": "71112e62807d1925dc3ae6188b11f8cfc85aec23"
            },
            {
              "fixed": "210d36d892de5195e6766c45519dfb1e65f3eb83"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
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              "introduced": "0"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
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          "type": "GIT"
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            },
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              "fixed": "4.20"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
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              "introduced": "5.4.1"
            },
            {
              "fixed": "5.5"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.5.0"
            },
            {
              "fixed": "5.10.253"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.203"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.168"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.131"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.80"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.21"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31555.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Clear stale exiting pointer in futex_lock_pi() retry path\n\nFuzzying/stressing futexes triggered:\n\n    WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524\n\nWhen futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY\nand stores a refcounted task pointer in 'exiting'.\n\nAfter wait_for_owner_exiting() consumes that reference, the local pointer\nis never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a\ndifferent error, the bogus pointer is passed to wait_for_owner_exiting().\n\n  CPU0\t\t\t     CPU1\t\t       CPU2\n  futex_lock_pi(uaddr)\n  // acquires the PI futex\n  exit()\n    futex_cleanup_begin()\n      futex_state = EXITING;\n\t\t\t     futex_lock_pi(uaddr)\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t attach_to_pi_owner()\n\t\t\t\t   // observes EXITING\n\t\t\t\t   *exiting = owner;  // takes ref\n\t\t\t\t   return -EBUSY\n\t\t\t       wait_for_owner_exiting(-EBUSY, owner)\n\t\t\t\t put_task_struct();   // drops ref\n\t\t\t       // exiting still points to owner\n\t\t\t       goto retry;\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t lock_pi_update_atomic()\n\t\t\t\t   cmpxchg(uaddr)\n\t\t\t\t\t*uaddr ^= WAITERS // whatever\n\t\t\t\t   // value changed\n\t\t\t\t return -EAGAIN;\n\t\t\t       wait_for_owner_exiting(-EAGAIN, exiting) // stale\n\t\t\t\t WARN_ON_ONCE(exiting)\n\nFix this by resetting upon retry, essentially aligning it with requeue_pi.",
  "id": "CVE-2026-31555",
  "modified": "2026-07-08T05:36:54.987421132Z",
  "published": "2026-04-24T14:35:39.211Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/210d36d892de5195e6766c45519dfb1e65f3eb83"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5e8e06bf8909e79b4acd950cf578cfc2f10bbefa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/71112e62807d1925dc3ae6188b11f8cfc85aec23"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7475dfad10a05a5bfadebf5f2499bd61b19ed293"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/92e47ad03e03dbb5515bdf06444bf6b1e147310d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de7c0c04ad868f2cee6671b11c0a6d20421af1da"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7824ec168d2ac883a213cd1f4d6cc0816002a85"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31555.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31555"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "futex: Clear stale exiting pointer in futex_lock_pi() retry path"
}