{ "id": "CVE-2021-29492", "sourceIdentifier": "security-advisories@github.com", "published": "2021-05-28T21:15:08.670", "lastModified": "2021-12-10T18:10:32.253", "vulnStatus": "Analyzed", "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": "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", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW", "baseScore": 8.3, "baseSeverity": "HIGH" }, "exploitabilityScore": 3.9, "impactScore": 3.7 }, { "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", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH" }, "exploitabilityScore": 2.2, "impactScore": 5.9 } ], "cvssMetricV2": [ { "source": "nvd@nist.gov", "type": "Primary", "cvssData": { "version": "2.0", "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P", "accessVector": "NETWORK", "accessComplexity": "LOW", "authentication": "NONE", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "availabilityImpact": "PARTIAL", "baseScore": 7.5 }, "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": "Primary", "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" ] } ] }