Description
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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| envoyproxy | envoy | >= 1.38.0, < 1.38.1, >= 1.37.0, < 1.37.3, >= 1.36.0, < 1.36.7, < 1.35.11 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | istioctl | 1.30.2-1.1 | openSUSE-SU-2026:11141-1 |
Advisories 2
- WID-SEC-2026-2048 Google Cloud Service Mesh und Envoy Proxy: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 3, 2026
- openSUSE-SU-2026:11141-1 istioctl-1.30.2-1.1 on GA media SUSE / openSUSE Security Updates · Jun 29, 2026