CVE-2026-73552 Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy HTTP RBAC accepts RFC-valid opaque header bytes but evaluates saferegex values with RE2's UTF-8 subject semantics. A downstream client can preserve a prohibit...