CVE-2021-29492
Vulnerability from cvelistv5
Published
2021-05-28 21:00
Modified
2024-08-03 22:11
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\` interchangeably.
References
security-advisories@github.comhttps://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cfMitigation, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cfMitigation, Third Party Advisory
Impacted products
Vendor Product Version
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T22:11:05.253Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c= 1.18.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\\` interchangeably."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-06-07T11:25:20",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf"
        }
      ],
      "source": {
        "advisory": "GHSA-4987-27fx-x6cf",
        "discovery": "UNKNOWN"
      },
      "title": "Bypass of path matching rules using escaped slash characters",
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security-advisories@github.com",
          "ID": "CVE-2021-29492",
          "STATE": "PUBLIC",
          "TITLE": "Bypass of path matching rules using escaped slash characters"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "envoy",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "\u003c= 1.18.2"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "envoyproxy"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\\` interchangeably."
            }
          ]
        },
        "impact": {
          "cvss": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf",
              "refsource": "CONFIRM",
              "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf"
            }
          ]
        },
        "source": {
          "advisory": "GHSA-4987-27fx-x6cf",
          "discovery": "UNKNOWN"
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2021-29492",
    "datePublished": "2021-05-28T21:00:24",
    "dateReserved": "2021-03-30T00:00:00",
    "dateUpdated": "2024-08-03T22:11:05.253Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2021-29492\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2021-05-28T21:15:08.670\",\"lastModified\":\"2024-11-21T06:01:14.917\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\\\\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\\\\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\\\\` interchangeably.\"},{\"lang\":\"es\",\"value\":\"Envoy es un proxy de borde/medio/servicio nativo de la nube. Envoy no descifra las secuencias de barras diagonales escapadas `%2F` y `%5C` en las rutas URL HTTP en las versiones 1.18.2 y anteriores. Un atacante remoto puede crear una ruta con barras escapadas, por ejemplo `algo%2F..%2Fadmin`, para saltarse el control de acceso, por ejemplo, un bloqueo en `/admin`. Un servidor backend podr\u00eda entonces decodificar las secuencias de barras y normalizar la ruta y proporcionar a un atacante acceso m\u00e1s all\u00e1 del alcance previsto por la pol\u00edtica de control de acceso. ### Impacto Escalada de Privilegios cuando se utilizan filtros RBAC o JWT con aplicaci\u00f3n basada en la ruta de la URL. Los usuarios con servidores de back-end que interpretan `%2F` y `/` y `%5C` y `\\\\` indistintamente est\u00e1n impactados. ### Vector de ataque Rutas de URL que contienen caracteres de barra diagonal escapados entregados por un cliente que no es de confianza. Los parches de las versiones 1.18.3, 1.17.3, 1.16.4 y 1.15.5 contienen una nueva opci\u00f3n de normalizaci\u00f3n de rutas para descodificar los caracteres de barra diagonal escapados. Como soluci\u00f3n, si los servidores finales tratan `%2F` y `/` y `%5C` y `\\\\` indistintamente y se configura un control de acceso basado en la ruta de la URL, se puede reconfigurar el servidor final para que no trate `%2F` y `/` y `%5C` y `\\\\` indistintamente\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.2,\"impactScore\":5.9},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L\",\"baseScore\":8.3,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":3.9,\"impactScore\":3.7}],\"cvssMetricV2\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"2.0\",\"vectorString\":\"AV:N/AC:L/Au:N/C:P/I:P/A:P\",\"baseScore\":7.5,\"accessVector\":\"NETWORK\",\"accessComplexity\":\"LOW\",\"authentication\":\"NONE\",\"confidentialityImpact\":\"PARTIAL\",\"integrityImpact\":\"PARTIAL\",\"availabilityImpact\":\"PARTIAL\"},\"baseSeverity\":\"HIGH\",\"exploitabilityScore\":10.0,\"impactScore\":6.4,\"acInsufInfo\":false,\"obtainAllPrivilege\":false,\"obtainUserPrivilege\":false,\"obtainOtherPrivilege\":false,\"userInteractionRequired\":false}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-22\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"1.15.5\",\"matchCriteriaId\":\"EE9E311E-85FF-42AA-B0A3-C138D436932D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"1.16.0\",\"versionEndExcluding\":\"1.16.4\",\"matchCriteriaId\":\"D36D66BB-9C95-4E59-AA78-6824ACCB89D7\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"1.17.0\",\"versionEndExcluding\":\"1.17.3\",\"matchCriteriaId\":\"D502D5F9-38A7-46B1-890D-2A177B76AEBB\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"1.18.0\",\"versionEndExcluding\":\"1.18.3\",\"matchCriteriaId\":\"BA3D8EC7-7D60-41C5-9770-3521DB6F7650\"}]}]}],\"references\":[{\"url\":\"https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Mitigation\",\"Third Party Advisory\"]},{\"url\":\"https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mitigation\",\"Third Party Advisory\"]}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.