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.
NVD Severity
Other trackers
Mailing lists
GitHub (code, issues), Aports (code, issues)


Type URI

Match rules

CPE URI Source package Min version Max version
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* envoy >= None < 1.15.5
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* envoy >= 1.16.0 < 1.16.4
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* envoy >= 1.17.0 < 1.17.3
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* envoy >= 1.18.0 < 1.18.3

Vulnerable and fixed packages

Source package Branch Version Maintainer Status