CVE-2026-47775: Envoyproxy Envoy

Medium severity, CVSS 6.8. EPSS: 0.2% chance of exploitation in the next 30 days.

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 successful decryption and HTTP 401 on padding failure, creating a padding oracle. An attacker who obtains the encrypted CodeVerifier cookie can recover the plaintext PKCE code_verifier in ~6,200 requests (~100 seconds), then exchange it with a stolen authorization code to obtain the victim's access token. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.

Affected products

• Envoyproxy Envoy: from 1.35.0, before 1.35.11 (fixed in 1.35.11); from 1.36.0, before 1.36.7 (fixed in 1.36.7); from 1.37.0, before 1.37.3 (fixed in 1.37.3); from 1.38.0, before 1.38.1 (fixed in 1.38.1)

Published 2026-06-26. Last modified 2026-06-29.