CVE-2021-0920 (GCVE-0-2021-0920)

Vulnerability from cvelistv5 – Published: 2021-12-15 18:05 – Updated: 2025-10-21 23:15
VLAI CISA KEV
Summary
In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel
Severity
6.4 (Medium)
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: active Automatable: no Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
  • Elevation of privilege
  • CWE-416 - Use After Free
Assigner
References
Impacted products
Vendor Product Version
n/a Android Affected: Android kernel
CISA KEV
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: fb26cf7c-2569-40f7-8c45-7b65c2a1b543

Vulnerability ID: CVE-2021-0920

Status: Confirmed

Status Updated: 2022-05-23 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2022-05-23
Asserted: 2022-05-23
Scope
Notes: KEV entry: Android Kernel Race Condition Vulnerability | Affected: Android / Kernel | Description: Android kernel contains a race condition, which allows for a use-after-free vulnerability. Exploitation can allow for privilege escalation. | Required action: Apply updates per vendor instructions. | Due date: 2022-06-13 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): https://nvd.nist.gov/vuln/detail/CVE-2021-0920
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-362 CWE-416
Feed CISA Known Exploited Vulnerabilities Catalog
Product Kernel
Due Date 2022-06-13
Date Added 2022-05-23
Vendorproject Android
Vulnerabilityname Android Kernel Race Condition Vulnerability
Knownransomwarecampaignuse Unknown
References
Created: 2026-02-02 13:25 UTC | Updated: 2026-02-06 07:53 UTC
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T15:55:16.898Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://source.android.com/security/bulletin/2021-11-01"
          },
          {
            "name": "[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update",
            "tags": [
              "mailing-list",
              "x_refsource_MLIST",
              "x_transferred"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 6.4,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "HIGH",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2021-0920",
                "options": [
                  {
                    "Exploitation": "active"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-02-06T16:18:51.272894Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          },
          {
            "other": {
              "content": {
                "dateAdded": "2022-05-23",
                "reference": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920"
              },
              "type": "kev"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-416",
                "description": "CWE-416 Use After Free",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-10-21T23:15:50.498Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "government-resource"
            ],
            "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2022-05-23T00:00:00.000Z",
            "value": "CVE-2021-0920 added to CISA KEV"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Android",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "Android kernel"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "Elevation of privilege",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-12-17T00:06:43.000Z",
        "orgId": "baff130e-b8d5-4e15-b3d3-c3cf5d5545c6",
        "shortName": "google_android"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://source.android.com/security/bulletin/2021-11-01"
        },
        {
          "name": "[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update",
          "tags": [
            "mailing-list",
            "x_refsource_MLIST"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security@android.com",
          "ID": "CVE-2021-0920",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "Android",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "Android kernel"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "n/a"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel"
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "Elevation of privilege"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://source.android.com/security/bulletin/2021-11-01",
              "refsource": "MISC",
              "url": "https://source.android.com/security/bulletin/2021-11-01"
            },
            {
              "name": "[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update",
              "refsource": "MLIST",
              "url": "https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "baff130e-b8d5-4e15-b3d3-c3cf5d5545c6",
    "assignerShortName": "google_android",
    "cveId": "CVE-2021-0920",
    "datePublished": "2021-12-15T18:05:31.000Z",
    "dateReserved": "2020-11-06T00:00:00.000Z",
    "dateUpdated": "2025-10-21T23:15:50.498Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "cisa_known_exploited": {
      "cveID": "CVE-2021-0920",
      "cwes": "[\"CWE-362\", \"CWE-416\"]",
      "dateAdded": "2022-05-23",
      "dueDate": "2022-06-13",
      "knownRansomwareCampaignUse": "Unknown",
      "notes": "https://nvd.nist.gov/vuln/detail/CVE-2021-0920",
      "product": "Kernel",
      "requiredAction": "Apply updates per vendor instructions.",
      "shortDescription": "Android kernel contains a race condition, which allows for a use-after-free vulnerability. Exploitation can allow for privilege escalation.",
      "vendorProject": "Android",
      "vulnerabilityName": "Android Kernel Race Condition Vulnerability"
    },
    "epss": {
      "cve": "CVE-2021-0920",
      "date": "2026-06-04",
      "epss": "0.00933",
      "percentile": "0.76516"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2021-0920\",\"sourceIdentifier\":\"security@android.com\",\"published\":\"2021-12-15T19:15:11.017\",\"lastModified\":\"2025-10-23T14:53:26.187\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel\"},{\"lang\":\"es\",\"value\":\"En la funci\u00f3n unix_scm_to_skb del archivo af_unix.c, se presenta un posible error de uso de memoria previamente liberada debido a una condici\u00f3n de carrera. Esto podr\u00eda conllevar a una escalada local de privilegios con los privilegios de ejecuci\u00f3n System requeridos. No es requerida una interacci\u00f3n del usuario para su explotaci\u00f3n. Producto: Android. Versiones: Android kernel. ID de Android: A-196926917 Referencias: Kernel ascendente\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":6.4,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"HIGH\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":0.5,\"impactScore\":5.9},{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":6.4,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"HIGH\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":0.5,\"impactScore\":5.9}],\"cvssMetricV2\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"2.0\",\"vectorString\":\"AV:L/AC:M/Au:N/C:C/I:C/A:C\",\"baseScore\":6.9,\"accessVector\":\"LOCAL\",\"accessComplexity\":\"MEDIUM\",\"authentication\":\"NONE\",\"confidentialityImpact\":\"COMPLETE\",\"integrityImpact\":\"COMPLETE\",\"availabilityImpact\":\"COMPLETE\"},\"baseSeverity\":\"MEDIUM\",\"exploitabilityScore\":3.4,\"impactScore\":10.0,\"acInsufInfo\":false,\"obtainAllPrivilege\":false,\"obtainUserPrivilege\":false,\"obtainOtherPrivilege\":false,\"userInteractionRequired\":false}]},\"cisaExploitAdd\":\"2022-05-23\",\"cisaActionDue\":\"2022-06-13\",\"cisaRequiredAction\":\"Apply updates per vendor instructions.\",\"cisaVulnerabilityName\":\"Android Kernel Race Condition Vulnerability\",\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-362\"},{\"lang\":\"en\",\"value\":\"CWE-416\"}]},{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionEndIncluding\":\"5.13\",\"matchCriteriaId\":\"427127D4-0234-4F80-B486-3D7564BD965F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:5.14:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"71268287-21A8-4488-AA4F-23C473153131\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:5.14:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"23B9E5C6-FAB5-4A02-9E39-27C8787B0991\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:5.14:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"D185CF67-7E4A-4154-93DB-CE379C67DB56\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:google:android:-:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"F8B9FEC8-73B6-43B8-B24E-1F7C20D91D26\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"DEECE5FC-CACF-4496-A3E7-164736409252\"}]}]}],\"references\":[{\"url\":\"https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html\",\"source\":\"security@android.com\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://source.android.com/security/bulletin/2021-11-01\",\"source\":\"security@android.com\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://source.android.com/security/bulletin/2021-11-01\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"tags\":[\"Third Party Advisory\",\"US Government Resource\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"https://source.android.com/security/bulletin/2021-11-01\", \"tags\": [\"x_refsource_MISC\", \"x_transferred\"]}, {\"url\": \"https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html\", \"name\": \"[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update\", \"tags\": [\"mailing-list\", \"x_refsource_MLIST\", \"x_transferred\"]}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2024-08-03T15:55:16.898Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 6.4, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"HIGH\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2021-0920\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"active\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2024-02-06T16:18:51.272894Z\"}}}, {\"other\": {\"type\": \"kev\", \"content\": {\"dateAdded\": \"2022-05-23\", \"reference\": \"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920\"}}}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2022-05-23T00:00:00.000Z\", \"value\": \"CVE-2021-0920 added to CISA KEV\"}], \"references\": [{\"url\": \"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920\", \"tags\": [\"government-resource\"]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416 Use After Free\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-02-04T19:03:46.630Z\"}}], \"cna\": {\"affected\": [{\"vendor\": \"n/a\", \"product\": \"Android\", \"versions\": [{\"status\": \"affected\", \"version\": \"Android kernel\"}]}], \"references\": [{\"url\": \"https://source.android.com/security/bulletin/2021-11-01\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html\", \"name\": \"[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update\", \"tags\": [\"mailing-list\", \"x_refsource_MLIST\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"text\", \"description\": \"Elevation of privilege\"}]}], \"providerMetadata\": {\"orgId\": \"baff130e-b8d5-4e15-b3d3-c3cf5d5545c6\", \"shortName\": \"google_android\", \"dateUpdated\": \"2021-12-17T00:06:43.000Z\"}, \"x_legacyV4Record\": {\"affects\": {\"vendor\": {\"vendor_data\": [{\"product\": {\"product_data\": [{\"version\": {\"version_data\": [{\"version_value\": \"Android kernel\"}]}, \"product_name\": \"Android\"}]}, \"vendor_name\": \"n/a\"}]}}, \"data_type\": \"CVE\", \"references\": {\"reference_data\": [{\"url\": \"https://source.android.com/security/bulletin/2021-11-01\", \"name\": \"https://source.android.com/security/bulletin/2021-11-01\", \"refsource\": \"MISC\"}, {\"url\": \"https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html\", \"name\": \"[debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security update\", \"refsource\": \"MLIST\"}]}, \"data_format\": \"MITRE\", \"description\": {\"description_data\": [{\"lang\": \"eng\", \"value\": \"In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel\"}]}, \"problemtype\": {\"problemtype_data\": [{\"description\": [{\"lang\": \"eng\", \"value\": \"Elevation of privilege\"}]}]}, \"data_version\": \"4.0\", \"CVE_data_meta\": {\"ID\": \"CVE-2021-0920\", \"STATE\": \"PUBLIC\", \"ASSIGNER\": \"security@android.com\"}}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-0920\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-10-21T23:15:50.498Z\", \"dateReserved\": \"2020-11-06T00:00:00.000Z\", \"assignerOrgId\": \"baff130e-b8d5-4e15-b3d3-c3cf5d5545c6\", \"datePublished\": \"2021-12-15T18:05:31.000Z\", \"assignerShortName\": \"google_android\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}


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.


Detection rules are retrieved from Rulezet.