CVE-2026-47775
Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption
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.
INFO
Published Date :
June 26, 2026, 6:16 p.m.
Last Modified :
June 29, 2026, 6:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Envoy to version 1.35.11 or later.
- Update Envoy to version 1.36.7 or later.
- Update Envoy to version 1.37.3 or later.
- Update Envoy to version 1.38.1 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-47775.
| URL | Resource |
|---|---|
| https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p | Exploit Vendor Advisory Mitigation |
| https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p | Exploit Vendor Advisory Mitigation |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-47775 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-47775
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-47775 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-47775 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 29, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.36.0 up to (excluding) 1.36.7 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.37.0 up to (excluding) 1.37.3 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.38.0 up to (excluding) 1.38.1 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.35.0 up to (excluding) 1.35.11 Added Reference Type GitHub, Inc.: https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p Types: Exploit, Mitigation, Vendor Advisory Added Reference Type CISA-ADP: https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p Types: Exploit, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 29, 2026
Action Type Old Value New Value Added Reference https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p Added SSVC {'id': 'CVE-2026-47775', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-29T15:05:22.645121Z'} -
New CVE Received by [email protected]
Jun. 26, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'envoyproxy', 'product': 'envoy', 'versions': [{'status': 'affected', 'version': '>= 1.38.0, < 1.38.1'}, {'status': 'affected', 'version': '>= 1.37.0, < 1.37.3'}, {'status': 'affected', 'version': '>= 1.36.0, < 1.36.7'}, {'status': 'affected', 'version': '< 1.35.11'}]}] Added 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. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N Added CWE CWE-327 Added CWE CWE-209 Added Reference https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p