CVE-2023-27487: Envoy client may fake the header `x-envoy-original-path`

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-04-04 · updated 2026-06-17
Weakness: CWE-20

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, the client may bypass JSON Web Token (JWT) checks and forge fake original paths. The header `x-envoy-original-path` should be an internal header, but Envoy does not remove this header from the request at the beginning of request processing when it is sent from an untrusted client. The faked header would then be used for trace logs and grpc logs, as well as used in the URL used for `jwt_authn` checks if the `jwt_authn` filter is used, and any other upstream use of the x-envoy-original-path header. Attackers may forge a trusted `x-envoy-original-path` header. Versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9 have patches for this issue.

Affected products

envoyproxy envoy: before 1.22.9; from 1.23.0 before 1.23.6; from 1.24.0 before 1.24.4; from 1.25.0 before 1.25.3 — fixed in 1.22.9, 1.23.6, 1.24.4, 1.25.3

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.22.9, 1.23.6, 1.24.4, 1.25.3. Check the vendor advisory for mitigations.

References

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