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.
History

No history.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2021-05-28T21:00:24

Updated: 2024-08-03T22:11:05.253Z

Reserved: 2021-03-30T00:00:00

Link: CVE-2021-29492

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2021-05-28T21:15:08.670

Modified: 2021-12-10T18:10:32.253

Link: CVE-2021-29492

cve-icon Redhat

Severity : Important

Publid Date: 2021-05-11T19:00:00Z

Links: CVE-2021-29492 - Bugzilla