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CVE-2021-39933

Status: ModifiedMedium (6.5)—

An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.10 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. A regular expression used for handling user input (notes, comments, etc) was susceptible to catastrophic backtracking that could cause a DOS attack.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Gitlab — Gitlab

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-39933",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 4,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:S/C:N/I:N/A:P",
          "authentication": "SINGLE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "cve@gitlab.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "LOW",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.5,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "cve@gitlab.com",
      "affectedData": [
        {
          "vendor": "GitLab",
          "product": "GitLab",
          "versions": [
            {
              "status": "affected",
              "version": ">=12.10, <14.3.6"
            },
            {
              "status": "affected",
              "version": ">=14.4, <14.4.4"
            },
            {
              "status": "affected",
              "version": ">=14.5, <14.5.2"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-12-13T16:15:09.250",
  "references": [
    {
      "url": "https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39933.json",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "cve@gitlab.com"
    },
    {
      "url": "https://gitlab.com/gitlab-org/gitlab/-/issues/340449",
      "tags": [
        "Broken Link"
      ],
      "source": "cve@gitlab.com"
    },
    {
      "url": "https://hackerone.com/reports/1320077",
      "tags": [
        "Permissions Required",
        "Third Party Advisory"
      ],
      "source": "cve@gitlab.com"
    },
    {
      "url": "https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39933.json",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://gitlab.com/gitlab-org/gitlab/-/issues/340449",
      "tags": [
        "Broken Link"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://hackerone.com/reports/1320077",
      "tags": [
        "Permissions Required",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.10 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. A regular expression used for handling user input (notes, comments, etc) was susceptible to catastrophic backtracking that could cause a DOS attack."
    },
    {
      "lang": "es",
      "value": "Se ha detectado un problema en GitLab CE/EE afectando a todas las versiones a partir de 12.10 anteriores a 14.3.6, a todas las versiones a partir de 14.4 anteriores a 14.4.4, a todas las versiones a partir de 14.5 anteriores a 14.5.2. Una expresión regular usada para el manejo de la entrada del usuario (notas, comentarios, etc) era susceptible de un retroceso catastrófico que podía causar un ataque DOS"
    }
  ],
  "lastModified": "2026-06-17T04:04:27.160",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "F093F933-8552-46D5-8B05-34587C104DFF",
              "versionEndExcluding": "14.3.6",
              "versionStartIncluding": "12.10.0"
            },
            {
              "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "47495883-D8D0-485E-9920-993CF00199FF",
              "versionEndExcluding": "14.3.6",
              "versionStartIncluding": "12.10.0"
            },
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              "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "1E801B5F-9C94-4CB2-89ED-D071E567132C",
              "versionEndExcluding": "14.4.4",
              "versionStartIncluding": "14.4.0"
            },
            {
              "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "7C38F838-02EA-4E2F-8493-57DD401EF911",
              "versionEndExcluding": "14.4.4",
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              "vulnerable": true,
              "matchCriteriaId": "95F59DF7-707C-4C43-8352-8115DAF1C533",
              "versionEndExcluding": "14.5.2",
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              "versionEndExcluding": "14.5.2",
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          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@gitlab.com"
}