CVE-2021-47577 (GCVE-0-2021-47577)

Vulnerability from cvelistv5 – Published: 2024-06-19 14:53 – Updated: 2026-08-05 08:48
VLAI
Title
io-wq: check for wq exit after adding new worker task_work
Summary
In the Linux kernel, the following vulnerability has been resolved: io-wq: check for wq exit after adding new worker task_work We check IO_WQ_BIT_EXIT before attempting to create a new worker, and wq exit cancels pending work if we have any. But it's possible to have a race between the two, where creation checks exit finding it not set, but we're in the process of exiting. The exit side will cancel pending creation task_work, but there's a gap where we add task_work after we've canceled existing creations at exit time. Fix this by checking the EXIT bit post adding the creation task_work. If it's set, run the same cancelation that exit does.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-06-21 14:05 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 685fe7feedb96771683437107ba72131410e2350 , < 4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec (git)
Affected: 685fe7feedb96771683437107ba72131410e2350 , < 71a85387546e50b1a37b0fa45dadcae3bfb35cf6 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.13
Unaffected: 0 , < 5.13 (semver)
Unaffected: 5.15.11 , ≤ 5.15.* (semver)
Unaffected: 5.16 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2021-47577",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-06-21T14:05:50.192086Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2024-06-21T14:06:00.767Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T05:39:59.773Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/io-wq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec",
              "status": "affected",
              "version": "685fe7feedb96771683437107ba72131410e2350",
              "versionType": "git"
            },
            {
              "lessThan": "71a85387546e50b1a37b0fa45dadcae3bfb35cf6",
              "status": "affected",
              "version": "685fe7feedb96771683437107ba72131410e2350",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/io-wq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.13"
            },
            {
              "lessThan": "5.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "5.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.11",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.16",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio-wq: check for wq exit after adding new worker task_work\n\nWe check IO_WQ_BIT_EXIT before attempting to create a new worker, and\nwq exit cancels pending work if we have any. But it\u0027s possible to have\na race between the two, where creation checks exit finding it not set,\nbut we\u0027re in the process of exiting. The exit side will cancel pending\ncreation task_work, but there\u0027s a gap where we add task_work after we\u0027ve\ncanceled existing creations at exit time.\n\nFix this by checking the EXIT bit post adding the creation task_work.\nIf it\u0027s set, run the same cancelation that exit does."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is in io-wq worker creation used by io_uring and is reached only through local syscalls (io_uring_setup/io_uring_enter), not via network packet processing.\nAC:L - Although this is a race between worker creation and wq exit, the attacker controls both sides by submitting async io_uring work while concurrently exiting/closing the ring, and syzbot produced a C repro that triggers the UAF.\nPR:L - Basic io_uring_setup requires no capabilities; unprivileged local users can create rings and drive io-wq (io_uring_disabled was added years later and defaults to allowing all users).\nUI:N - Exploitation is entirely via the attacker\u0027s own io_uring syscalls and process lifecycle; no victim action is required.\nS:U - Impact stays within the host kernel authority (local memory corruption / privilege escalation / DoS), with no VM escape or other cross-boundary scope change.\nC:H - Syzbot confirmed a use-after-free write on a freed kmalloc-512 io_worker; UAF enables heap reuse and arbitrary kernel memory read primitives.\nI:H - The UAF write through freed worker create_state/task_work state can be turned into an arbitrary write and control-flow hijack via heap spraying of the reused object.\nA:H - The UAF causes kernel oops/panic under KASAN and can crash or hang the system even when not fully exploited for code execution."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:48:27.449Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
        },
        {
          "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
        }
      ],
      "title": "io-wq: check for wq exit after adding new worker task_work",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2021-47577",
    "datePublished": "2024-06-19T14:53:45.393Z",
    "dateReserved": "2024-05-24T15:11:00.730Z",
    "dateUpdated": "2026-08-05T08:48:27.449Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2021-47577",
      "date": "2026-09-25",
      "epss": "0.0015",
      "percentile": "0.03486"
    },
    "fkie_nvd": {
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio-wq: check for wq exit after adding new worker task_work\n\nWe check IO_WQ_BIT_EXIT before attempting to create a new worker, and\nwq exit cancels pending work if we have any. But it\u0027s possible to have\na race between the two, where creation checks exit finding it not set,\nbut we\u0027re in the process of exiting. The exit side will cancel pending\ncreation task_work, but there\u0027s a gap where we add task_work after we\u0027ve\ncanceled existing creations at exit time.\n\nFix this by checking the EXIT bit post adding the creation task_work.\nIf it\u0027s set, run the same cancelation that exit does."
        },
        {
          "lang": "es",
          "value": "En el kernel de Linux se ha resuelto la siguiente vulnerabilidad: io-wq: comprueba la salida de wq despu\u00e9s de agregar un nuevo trabajador task_work Comprobamos IO_WQ_BIT_EXIT antes de intentar crear un nuevo trabajador, y wq exit cancela el trabajo pendiente si tenemos alguno. Pero es posible tener una carrera entre los dos, donde las comprobaciones de creaci\u00f3n salen y descubren que no est\u00e1 configurado, pero estamos en el proceso de salir. El lado de salida cancelar\u00e1 la creaci\u00f3n pendiente task_work, pero hay un espacio en el que agregamos task_work despu\u00e9s de haber cancelado las creaciones existentes en el momento de la salida. Solucione este problema marcando la publicaci\u00f3n del bit EXIT agregando la tarea de creaci\u00f3n_trabajo. Si est\u00e1 configurado, ejecute la misma cancelaci\u00f3n que realiza la salida."
        }
      ],
      "id": "CVE-2021-47577",
      "lastModified": "2024-11-21T06:36:35.300",
      "published": "2024-06-19T15:15:52.223",
      "references": [
        {
          "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
        },
        {
          "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
        }
      ],
      "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "vulnStatus": "Awaiting Analysis"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "fs/io-wq.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec",
                    "status": "affected",
                    "version": "685fe7feedb96771683437107ba72131410e2350",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "71a85387546e50b1a37b0fa45dadcae3bfb35cf6",
                    "status": "affected",
                    "version": "685fe7feedb96771683437107ba72131410e2350",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "fs/io-wq.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "5.13"
                  },
                  {
                    "lessThan": "5.13",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.15.*",
                    "status": "unaffected",
                    "version": "5.15.11",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "5.16",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "B271E1AF-BC45-4C3E-9614-055846520592",
                    "versionEndExcluding": "5.15.11",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*",
                    "matchCriteriaId": "357AA433-37E8-4323-BFB2-3038D6E4B414",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:*",
                    "matchCriteriaId": "A73429BA-C2D9-4D0C-A75F-06A1CA8B3983",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:*",
                    "matchCriteriaId": "F621B5E3-E99D-49E7-90B9-EC3B77C95383",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:*",
                    "matchCriteriaId": "F7BFDCAA-1650-49AA-8462-407DD593F94F",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio-wq: check for wq exit after adding new worker task_work\n\nWe check IO_WQ_BIT_EXIT before attempting to create a new worker, and\nwq exit cancels pending work if we have any. But it\u0027s possible to have\na race between the two, where creation checks exit finding it not set,\nbut we\u0027re in the process of exiting. The exit side will cancel pending\ncreation task_work, but there\u0027s a gap where we add task_work after we\u0027ve\ncanceled existing creations at exit time.\n\nFix this by checking the EXIT bit post adding the creation task_work.\nIf it\u0027s set, run the same cancelation that exit does."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux se ha resuelto la siguiente vulnerabilidad: io-wq: comprueba la salida de wq despu\u00e9s de agregar un nuevo trabajador task_work Comprobamos IO_WQ_BIT_EXIT antes de intentar crear un nuevo trabajador, y wq exit cancela el trabajo pendiente si tenemos alguno. Pero es posible tener una carrera entre los dos, donde las comprobaciones de creaci\u00f3n salen y descubren que no est\u00e1 configurado, pero estamos en el proceso de salir. El lado de salida cancelar\u00e1 la creaci\u00f3n pendiente task_work, pero hay un espacio en el que agregamos task_work despu\u00e9s de haber cancelado las creaciones existentes en el momento de la salida. Solucione este problema marcando la publicaci\u00f3n del bit EXIT agregando la tarea de creaci\u00f3n_trabajo. Si est\u00e1 configurado, ejecute la misma cancelaci\u00f3n que realiza la salida."
          }
        ],
        "id": "CVE-2021-47577",
        "lastModified": "2026-08-04T10:17:09.370",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            },
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 4.7,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.0,
              "impactScore": 3.6,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2021-47577",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-06-21T14:05:50.192086Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2024-06-19T15:15:52.223",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-362"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-04T19:57:09+00:00",
      "cve": "CVE-2021-47577",
      "id": "CVE-2021-47577",
      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: io-wq: check for wq exit after adding new worker task_work",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47577.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T16:57:51Z",
      "cve": "CVE-2021-47577",
      "id": "CVE-2021-47577",
      "initial_release_date": "2024-06-21T03:52:38Z",
      "product_status:known_affected": "397",
      "product_status:known_not_affected": "294",
      "product_status:recommended": "298",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2021-47577",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-47577.json",
      "version": "52"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "providerMetadata": {
              "dateUpdated": "2024-08-04T05:39:59.773Z",
              "orgId": "af854a3a-2127-422b-91ae-364da2661108",
              "shortName": "CVE"
            },
            "references": [
              {
                "tags": [
                  "x_transferred"
                ],
                "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
              },
              {
                "tags": [
                  "x_transferred"
                ],
                "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
              }
            ],
            "title": "CVE Program Container"
          },
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2021-47577",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2024-06-21T14:05:50.192086Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2024-06-21T14:05:55.882Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "fs/io-wq.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec",
                  "status": "affected",
                  "version": "685fe7feedb96771683437107ba72131410e2350",
                  "versionType": "git"
                },
                {
                  "lessThan": "71a85387546e50b1a37b0fa45dadcae3bfb35cf6",
                  "status": "affected",
                  "version": "685fe7feedb96771683437107ba72131410e2350",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "fs/io-wq.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "5.13"
                },
                {
                  "lessThan": "5.13",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.11",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "5.16",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.11",
                      "versionStartIncluding": "5.13",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.16",
                      "versionStartIncluding": "5.13",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio-wq: check for wq exit after adding new worker task_work\n\nWe check IO_WQ_BIT_EXIT before attempting to create a new worker, and\nwq exit cancels pending work if we have any. But it\u0027s possible to have\na race between the two, where creation checks exit finding it not set,\nbut we\u0027re in the process of exiting. The exit side will cancel pending\ncreation task_work, but there\u0027s a gap where we add task_work after we\u0027ve\ncanceled existing creations at exit time.\n\nFix this by checking the EXIT bit post adding the creation task_work.\nIf it\u0027s set, run the same cancelation that exit does."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The bug is in io-wq worker creation used by io_uring and is reached only through local syscalls (io_uring_setup/io_uring_enter), not via network packet processing.\nAC:L - Although this is a race between worker creation and wq exit, the attacker controls both sides by submitting async io_uring work while concurrently exiting/closing the ring, and syzbot produced a C repro that triggers the UAF.\nPR:L - Basic io_uring_setup requires no capabilities; unprivileged local users can create rings and drive io-wq (io_uring_disabled was added years later and defaults to allowing all users).\nUI:N - Exploitation is entirely via the attacker\u0027s own io_uring syscalls and process lifecycle; no victim action is required.\nS:U - Impact stays within the host kernel authority (local memory corruption / privilege escalation / DoS), with no VM escape or other cross-boundary scope change.\nC:H - Syzbot confirmed a use-after-free write on a freed kmalloc-512 io_worker; UAF enables heap reuse and arbitrary kernel memory read primitives.\nI:H - The UAF write through freed worker create_state/task_work state can be turned into an arbitrary write and control-flow hijack via heap spraying of the reused object.\nA:H - The UAF causes kernel oops/panic under KASAN and can crash or hang the system even when not fully exploited for code execution."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T08:48:27.449Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/4b4e5bbf9386d4ec21d91c0cb0fd60b9bba778ec"
            },
            {
              "url": "https://git.kernel.org/stable/c/71a85387546e50b1a37b0fa45dadcae3bfb35cf6"
            }
          ],
          "title": "io-wq: check for wq exit after adding new worker task_work",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2021-47577",
        "datePublished": "2024-06-19T14:53:45.393Z",
        "dateReserved": "2024-05-24T15:11:00.730Z",
        "dateUpdated": "2026-08-05T08:48:27.449Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.