CVE-2026-53713

Envoy Gateway is an open source project for managing Envoy Proxy as a standalone or Kubernetes-based application gateway. Prior to 1.7.4 and 1.8.1, to_absolute_normalized_path in internal/gatewayapi/luavalidator/security.lua does not collapse redundant separators before is_critical_path evaluates Lua submitted through EnvoyExtensionPolicy during default Strict validation. Linux resolves a double-slash absolute path as the corresponding single-slash path, but the validator does not match the redundant-separator form, allowing submitted Lua to read arbitrary files from the gateway controller pod. Exposed files can include Kubernetes service-account tokens, TLS certificates, and process environment data, and the disclosed credentials can provide access to sensitive Kubernetes API Server or Gateway xDS server information. This issue is fixed in versions 1.7.4 and 1.8.1.

Envoy Gateway is an open source project for managing Envoy Proxy as a standalone or Kubernetes-based application gateway. Prior to 1.7.4 and 1.8.1, to_absolute_normalized_path in internal/gatewayapi/luavalidator/security.lua does not collapse redundant separators before is_critical_path evaluates Lua submitted through EnvoyExtensionPolicy during default Strict validation. Linux resolves a double-slash absolute path as the corresponding single-slash path, but the validator does not match the redundant-separator form, allowing submitted Lua to read arbitrary files from the gateway controller pod. Exposed files can include Kubernetes service-account tokens, TLS certificates, and process environment data, and the disclosed credentials can provide access to sensitive Kubernetes API Server or Gateway xDS server information. This issue is fixed in versions 1.7.4 and 1.8.1.

Impact

The to_absolute_normalized_path function (security.lua:28-43) does not collapse redundant path separators (// → /). On Linux, //etc/passwd is equivalent to /etc/passwd (POSIX path semantics), but is_critical_path fails to match the double-slash variant because //etc/passwd does not start with /etc/.

This allows Lua code submitted as an EnvoyExtensionPolicy to read arbitrary files from the gateway controller pod's filesystem during Strict validation (the default), including:

• /etc/passwd
• Kubernetes SA tokens via //var/run/secrets/kubernetes.io/serviceaccount/token
• TLS certificates via //certs/...
• Process environment via //proc/self/environ

These credentials can be used to read sensitive information from the K8s API Server or from the Gateway XDS server.

Patches

This has been patched in versions >= v1.7.4 and v1.8.1

• Collapse redundant path separators (// to /) so double-slash variants like //etc/passwd and //var/run/secrets/... are matched by the critical-path check.
• Rewrite the traversal check to reject any . or .. segment in any position and across both separator styles (catches /etc/./passwd, ./etc/passwd, /etc/.).

Workarounds

Please refer to the Warning section in Lua docs for measures to reduce risk.

Credits

Envoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.

Envoy Gateway is an open source project for managing Envoy Proxy as a standalone or Kubernetes-based application gateway. Prior to 1.7.4 and 1.8.1, to_absolute_normalized_path in internal/gatewayapi/luavalidator/security.lua does not collapse redundant separators before is_critical_path evaluates Lua submitted through EnvoyExtensionPolicy during default Strict validation. Linux resolves a double-slash absolute path as the corresponding single-slash path, but the validator does not match the redundant-separator form, allowing submitted Lua to read arbitrary files from the gateway controller pod. Exposed files can include Kubernetes service-account tokens, TLS certificates, and process environment data, and the disclosed credentials can provide access to sensitive Kubernetes API Server or Gateway xDS server information. This issue is fixed in versions 1.7.4 and 1.8.1.

Envoy Gateway is an open source project for managing Envoy Proxy as a standalone or Kubernetes-based application gateway. Prior to 1.7.4 and 1.8.1, to_absolute_normalized_path in internal/gatewayapi/luavalidator/security.lua does not collapse redundant separators before is_critical_path evaluates Lua submitted through EnvoyExtensionPolicy during default Strict validation. Linux resolves a double-slash absolute path as the corresponding single-slash path, but the validator does not match the redundant-separator form, allowing submitted Lua to read arbitrary files from the gateway controller pod. Exposed files can include Kubernetes service-account tokens, TLS certificates, and process environment data, and the disclosed credentials can provide access to sensitive Kubernetes API Server or Gateway xDS server information. This issue is fixed in versions 1.7.4 and 1.8.1.

Impact

The to_absolute_normalized_path function (security.lua:28-43) does not collapse redundant path separators (// → /). On Linux, //etc/passwd is equivalent to /etc/passwd (POSIX path semantics), but is_critical_path fails to match the double-slash variant because //etc/passwd does not start with /etc/.

This allows Lua code submitted as an EnvoyExtensionPolicy to read arbitrary files from the gateway controller pod's filesystem during Strict validation (the default), including:

• /etc/passwd
• Kubernetes SA tokens via //var/run/secrets/kubernetes.io/serviceaccount/token
• TLS certificates via //certs/...
• Process environment via //proc/self/environ

These credentials can be used to read sensitive information from the K8s API Server or from the Gateway XDS server.

Patches

This has been patched in versions >= v1.7.4 and v1.8.1

• Collapse redundant path separators (// to /) so double-slash variants like //etc/passwd and //var/run/secrets/... are matched by the critical-path check.
• Rewrite the traversal check to reject any . or .. segment in any position and across both separator styles (catches /etc/./passwd, ./etc/passwd, /etc/.).

Workarounds

Please refer to the Warning section in Lua docs for measures to reduce risk.

Credits

Envoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.