CVE-2026-47775 (GCVE-0-2026-47775)

Vulnerability from cvelistv5 – Published: 2026-06-26 17:23 – Updated: 2026-06-29 15:20
VLAI
Title
Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption
Summary
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.
Severity
6.8 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-29 15:05 UTC
CWE
  • CWE-209 - Generation of Error Message Containing Sensitive Information
  • CWE-327 - Use of a Broken or Risky Cryptographic Algorithm
Assigner
References
Impacted products
Vendor Product Version CPE status
envoyproxy envoy Affected: >= 1.38.0, < 1.38.1
Affected: >= 1.37.0, < 1.37.3
Affected: >= 1.36.0, < 1.36.7
Affected: < 1.35.11
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