CVE-2026-47775

Name of the Vulnerable Software and Affected Versions Envoy versions prior to 1.35.11 Envoy versions prior to 1.36.7 Envoy versions prior to 1.37.3 Envoy versions prior to 1.38.1

Description The OAuth2 HTTP filter uses AES-256-CBC in its encrypt() and decrypt() functions without an authentication tag, such as HMAC or AEAD (Authenticated Encryption with Associated Data). This implementation allows the /callback endpoint to return different HTTP responses based on decryption success (HTTP 302) or padding failure (HTTP 401), creating a padding oracle. An attacker with access to the encrypted CodeVerifier cookie can recover the plaintext PKCE code verifier through approximately 6,200 requests, which can then be used with a stolen authorization code to obtain a victim's access token.

Recommendations Update to version 1.35.11 Update to version 1.36.7 Update to version 1.37.3 Update to version 1.38.1