CVE-2026-47775 Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, the OAuth2 HTTP filter's encrypt/decrypt functions use AES-256-CBC without an authentication tag no HMAC, no AEAD. The /callback endpoint returns HTTP 302 on...

CVE-2026-47775

Envoy OAuth2 filter vulnerability (CVE-2026-47775): prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, the encrypt()/decrypt() path uses AES-256-CBC without an authentication tag (no HMAC/AEAD), enabling a padding oracle via the /callback endpoint. An attacker with the encrypted CodeVerifier ...