GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2020-26293 (GCVE-0-2020-26293)

Vulnerability from cvelistv5 – Published: 2021-01-04 18:20 – Updated: 2024-08-04 15:56
VLAI
Title
Possible XSS bypass if style tag is allowed
Summary
HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `<style>` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `<style>` tag so there is no risk if you have not explicitly allowed the `<style>` tag. The problem has been fixed in version 5.0.372.
Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
CWE
  • CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Assigner
References
Impacted products
Vendor Product Version CPE status
mganss HtmlSanitizer Affected: < 5.0.372
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T15:56:03.977Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://www.nuget.org/packages/HtmlSanitizer/"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "HtmlSanitizer",
          "vendor": "mganss",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 5.0.372"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `\u003cstyle\u003e` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `\u003cstyle\u003e` tag so there is no risk if you have not explicitly allowed the `\u003cstyle\u003e` tag. The problem has been fixed in version 5.0.372."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-74",
              "description": "CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-01-04T18:20:14.000Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.nuget.org/packages/HtmlSanitizer/"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
        }
      ],
      "source": {
        "advisory": "GHSA-8j9v-h2vp-2hhv",
        "discovery": "UNKNOWN"
      },
      "title": "Possible XSS bypass if style tag is allowed",
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security-advisories@github.com",
          "ID": "CVE-2020-26293",
          "STATE": "PUBLIC",
          "TITLE": "Possible XSS bypass if style tag is allowed"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "HtmlSanitizer",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "\u003c 5.0.372"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "mganss"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `\u003cstyle\u003e` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `\u003cstyle\u003e` tag so there is no risk if you have not explicitly allowed the `\u003cstyle\u003e` tag. The problem has been fixed in version 5.0.372."
            }
          ]
        },
        "impact": {
          "cvss": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N",
            "version": "3.1"
          }
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv",
              "refsource": "CONFIRM",
              "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
            },
            {
              "name": "https://www.nuget.org/packages/HtmlSanitizer/",
              "refsource": "MISC",
              "url": "https://www.nuget.org/packages/HtmlSanitizer/"
            },
            {
              "name": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372",
              "refsource": "MISC",
              "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
            },
            {
              "name": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8",
              "refsource": "MISC",
              "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
            }
          ]
        },
        "source": {
          "advisory": "GHSA-8j9v-h2vp-2hhv",
          "discovery": "UNKNOWN"
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2020-26293",
    "datePublished": "2021-01-04T18:20:14.000Z",
    "dateReserved": "2020-10-01T00:00:00.000Z",
    "dateUpdated": "2024-08-04T15:56:03.977Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2020-26293",
      "date": "2026-09-20",
      "epss": "0.00997",
      "percentile": "0.61217"
    },
    "fkie_nvd": {
      "configurations": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:htmlsanitizer_project:htmlsanitizer:*:*:*:*:*:*:*:*",
                  "matchCriteriaId": "FCB9D50C-682F-4B40-96E0-D15A1BE2A02F",
                  "versionEndExcluding": "5.0.372",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `\u003cstyle\u003e` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `\u003cstyle\u003e` tag so there is no risk if you have not explicitly allowed the `\u003cstyle\u003e` tag. The problem has been fixed in version 5.0.372."
        },
        {
          "lang": "es",
          "value": "HtmlSanitizer es una biblioteca .NET para limpiar fragmentos HTML y documentos de construcciones que pueden conllevar a ataques de tipo XSS.\u0026#xa0;En HtmlSanitizer versiones anteriores a 5.0.372, se presenta una posible omisi\u00f3n de XSS si la etiqueta de estilo es permitida.\u0026#xa0;Si ha permitido expl\u00edcitamente la etiqueta \"(style)\", un atacante podr\u00eda crear HTML que incluya un script despu\u00e9s de pasar a trav\u00e9s del sanitizador.\u0026#xa0;La configuraci\u00f3n predeterminada no permite la etiqueta \"(style)\", por lo que no existe riesgo si no ha permitido expl\u00edcitamente la etiqueta \"(style)\".\u0026#xa0;El problema ha sido corregido en la versi\u00f3n 5.0.372."
        }
      ],
      "id": "CVE-2020-26293",
      "lastModified": "2024-11-21T05:19:47.020",
      "metrics": {
        "cvssMetricV2": [
          {
            "acInsufInfo": false,
            "baseSeverity": "MEDIUM",
            "cvssData": {
              "accessComplexity": "MEDIUM",
              "accessVector": "NETWORK",
              "authentication": "NONE",
              "availabilityImpact": "NONE",
              "baseScore": 4.3,
              "confidentialityImpact": "NONE",
              "integrityImpact": "PARTIAL",
              "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
              "version": "2.0"
            },
            "exploitabilityScore": 8.6,
            "impactScore": 2.9,
            "obtainAllPrivilege": false,
            "obtainOtherPrivilege": false,
            "obtainUserPrivilege": false,
            "source": "nvd@nist.gov",
            "type": "Primary",
            "userInteractionRequired": true
          }
        ],
        "cvssMetricV31": [
          {
            "cvssData": {
              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.1,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "CHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N",
              "version": "3.1"
            },
            "exploitabilityScore": 1.6,
            "impactScore": 4.0,
            "source": "security-advisories@github.com",
            "type": "Secondary"
          },
          {
            "cvssData": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.1,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "CHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
              "version": "3.1"
            },
            "exploitabilityScore": 2.8,
            "impactScore": 2.7,
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      },
      "published": "2021-01-04T19:15:14.970",
      "references": [
        {
          "source": "security-advisories@github.com",
          "tags": [
            "Patch",
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
        },
        {
          "source": "security-advisories@github.com",
          "tags": [
            "Release Notes",
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
        },
        {
          "source": "security-advisories@github.com",
          "tags": [
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
        },
        {
          "source": "security-advisories@github.com",
          "tags": [
            "Product",
            "Third Party Advisory"
          ],
          "url": "https://www.nuget.org/packages/HtmlSanitizer/"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Patch",
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Release Notes",
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Third Party Advisory"
          ],
          "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Product",
            "Third Party Advisory"
          ],
          "url": "https://www.nuget.org/packages/HtmlSanitizer/"
        }
      ],
      "sourceIdentifier": "security-advisories@github.com",
      "vulnStatus": "Modified",
      "weaknesses": [
        {
          "description": [
            {
              "lang": "en",
              "value": "CWE-74"
            }
          ],
          "source": "security-advisories@github.com",
          "type": "Secondary"
        },
        {
          "description": [
            {
              "lang": "en",
              "value": "CWE-79"
            }
          ],
          "source": "nvd@nist.gov",
          "type": "Primary"
        }
      ]
    },
    "nvd": {
      "cve": {
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:htmlsanitizer_project:htmlsanitizer:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "FCB9D50C-682F-4B40-96E0-D15A1BE2A02F",
                    "versionEndExcluding": "5.0.372",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `\u003cstyle\u003e` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `\u003cstyle\u003e` tag so there is no risk if you have not explicitly allowed the `\u003cstyle\u003e` tag. The problem has been fixed in version 5.0.372."
          },
          {
            "lang": "es",
            "value": "HtmlSanitizer es una biblioteca .NET para limpiar fragmentos HTML y documentos de construcciones que pueden conllevar a ataques de tipo XSS.\u0026#xa0;En HtmlSanitizer versiones anteriores a 5.0.372, se presenta una posible omisi\u00f3n de XSS si la etiqueta de estilo es permitida.\u0026#xa0;Si ha permitido expl\u00edcitamente la etiqueta \"(style)\", un atacante podr\u00eda crear HTML que incluya un script despu\u00e9s de pasar a trav\u00e9s del sanitizador.\u0026#xa0;La configuraci\u00f3n predeterminada no permite la etiqueta \"(style)\", por lo que no existe riesgo si no ha permitido expl\u00edcitamente la etiqueta \"(style)\".\u0026#xa0;El problema ha sido corregido en la versi\u00f3n 5.0.372."
          }
        ],
        "id": "CVE-2020-26293",
        "lastModified": "2024-11-21T05:19:47.020",
        "metrics": {
          "cvssMetricV2": [
            {
              "acInsufInfo": false,
              "baseSeverity": "MEDIUM",
              "cvssData": {
                "accessComplexity": "MEDIUM",
                "accessVector": "NETWORK",
                "authentication": "NONE",
                "availabilityImpact": "NONE",
                "baseScore": 4.3,
                "confidentialityImpact": "NONE",
                "integrityImpact": "PARTIAL",
                "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
                "version": "2.0"
              },
              "exploitabilityScore": 8.6,
              "impactScore": 2.9,
              "obtainAllPrivilege": false,
              "obtainOtherPrivilege": false,
              "obtainUserPrivilege": false,
              "source": "nvd@nist.gov",
              "type": "Primary",
              "userInteractionRequired": true
            }
          ],
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 6.1,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "CHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 1.6,
              "impactScore": 4.0,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            },
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 6.1,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "LOW",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "CHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 2.7,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2021-01-04T19:15:14.970",
        "references": [
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch",
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes",
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Product",
              "Third Party Advisory"
            ],
            "url": "https://www.nuget.org/packages/HtmlSanitizer/"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Patch",
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/commit/a3a7602a44d4155d51ec0fbbedc2a49e9c7e2eb8"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Release Notes",
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/releases/tag/v5.0.372"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-8j9v-h2vp-2hhv"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Product",
              "Third Party Advisory"
            ],
            "url": "https://www.nuget.org/packages/HtmlSanitizer/"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-74"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          },
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-79"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    }
  }
}



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.


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.