FKIE_CVE-2023-40021

Vulnerability from fkie_nvd - Published: 2023-08-16 21:15 - Updated: 2026-06-17 06:15
Severity
5.3 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
5.3 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Summary
Oppia is an online learning platform. When comparing a received CSRF token against the expected token, Oppia uses the string equality operator (`==`), which is not safe against timing attacks. By repeatedly submitting invalid tokens, an attacker can brute-force the expected CSRF token character by character. Once they have recovered the token, they can then submit a forged request on behalf of a logged-in user and execute privileged actions on that user's behalf. In particular the function to validate received CSRF tokens is at `oppia.core.controllers.base.CsrfTokenManager.is_csrf_token_valid`. An attacker who can lure a logged-in Oppia user to a malicious website can perform any change on Oppia that the user is authorized to do, including changing profile information; creating, deleting, and changing explorations; etc. Note that the attacker cannot change a user's login credentials. An attack would need to complete within 1 second because every second, the time used in computing the token changes. This issue has been addressed in commit `b89bf80837` which has been included in release `3.3.2-hotfix-2`. Users are advised to upgrade. There are no known workarounds for this vulnerability.
References
security-advisories@github.comhttps://github.com/oppia/oppia/blob/3a05c3558a292f3db9e658e60e708c266c003fd0/core/controllers/base.py#L964-L990Product
security-advisories@github.comhttps://github.com/oppia/oppia/commit/b89bf808378c1236874b5797a7bda32c77b4af23Patch
security-advisories@github.comhttps://github.com/oppia/oppia/pull/18769Patch
security-advisories@github.comhttps://github.com/oppia/oppia/security/advisories/GHSA-49jp-pjc3-2532Exploit, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/oppia/oppia/blob/3a05c3558a292f3db9e658e60e708c266c003fd0/core/controllers/base.py#L964-L990Product
af854a3a-2127-422b-91ae-364da2661108https://github.com/oppia/oppia/commit/b89bf808378c1236874b5797a7bda32c77b4af23Patch
af854a3a-2127-422b-91ae-364da2661108https://github.com/oppia/oppia/pull/18769Patch
af854a3a-2127-422b-91ae-364da2661108https://github.com/oppia/oppia/security/advisories/GHSA-49jp-pjc3-2532Exploit, Vendor Advisory
Impacted products
Vendor Product Version
oppia oppia *
oppia oppia 3.3.2
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "oppia",
          "vendor": "oppia",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.1.0, \u003c 3.3.2-hotfix-2"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    },
    {
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:oppia:oppia:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unknown",
          "product": "oppia",
          "vendor": "oppia",
          "versions": [
            {
              "lessThan": "3.3.2",
              "status": "affected",
              "version": "1.1.0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:oppia:oppia:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "87F65B5D-6454-4E3C-A7A5-F1FEEC6DC78C",
              "versionEndExcluding": "3.3.2",
              "versionStartIncluding": "1.1.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:oppia:oppia:3.3.2:-:*:*:*:*:*:*",
              "matchCriteriaId": "7B0060B6-6E1F-4B0F-8A6B-3437450C94C3",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Oppia is an online learning platform. When comparing a received CSRF token against the expected token, Oppia uses the string equality operator (`==`), which is not safe against timing attacks. By repeatedly submitting invalid tokens, an attacker can brute-force the expected CSRF token character by character. Once they have recovered the token, they can then submit a forged request on behalf of a logged-in user and execute privileged actions on that user\u0027s behalf. In particular the function to validate received CSRF tokens is at `oppia.core.controllers.base.CsrfTokenManager.is_csrf_token_valid`. An attacker who can lure a logged-in Oppia user to a malicious website can perform any change on Oppia that the user is authorized to do, including changing profile information; creating, deleting, and changing explorations; etc. Note that the attacker cannot change a user\u0027s login credentials. An attack would need to complete within 1 second because every second, the time used in computing the token changes. This issue has been addressed in commit `b89bf80837` which has been included in release `3.3.2-hotfix-2`. Users are advised to upgrade. There are no known workarounds for this vulnerability."
    }
  ],
  "id": "CVE-2023-40021",
  "lastModified": "2026-06-17T06:15:47.100",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2023-40021",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2024-10-03T13:33:01.578679Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2023-08-16T21:15:09.880",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/oppia/oppia/blob/3a05c3558a292f3db9e658e60e708c266c003fd0/core/controllers/base.py#L964-L990"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
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      "url": "https://github.com/oppia/oppia/commit/b89bf808378c1236874b5797a7bda32c77b4af23"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
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      "url": "https://github.com/oppia/oppia/pull/18769"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/oppia/oppia/security/advisories/GHSA-49jp-pjc3-2532"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/oppia/oppia/blob/3a05c3558a292f3db9e658e60e708c266c003fd0/core/controllers/base.py#L964-L990"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/oppia/oppia/commit/b89bf808378c1236874b5797a7bda32c77b4af23"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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      "url": "https://github.com/oppia/oppia/pull/18769"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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      "url": "https://github.com/oppia/oppia/security/advisories/GHSA-49jp-pjc3-2532"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-203"
        },
        {
          "lang": "en",
          "value": "CWE-208"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-203"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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