Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Envoyproxy | Envoy | >= 1.35.0, < 1.35.11 |
Related Weaknesses (CWE)
References
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7pExploitVendor AdvisoryMitigation
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7pExploitVendor AdvisoryMitigation
FAQ
What is CVE-2026-47775?
CVE-2026-47775 is a vulnerability with a CVSS score of 6.8 (MEDIUM). 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-...
How severe is CVE-2026-47775?
CVE-2026-47775 has been rated MEDIUM with a CVSS base score of 6.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-47775?
Check the references section above for vendor advisories and patch information. Affected products include: Envoyproxy Envoy.