CVE-2026-47775: CWE-209: Generation of Error Message Containing Sensitive Information in envoyproxy envoy
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.
AI Analysis
Technical Summary
The vulnerability (CVE-2026-47775) in envoyproxy envoy affects the OAuth2 HTTP filter's encryption and decryption functions that use AES-256-CBC without an authentication tag (no HMAC or AEAD). The /callback endpoint returns distinct HTTP status codes (302 on success, 401 on padding failure), creating a padding oracle side channel. An attacker who obtains the encrypted CodeVerifier cookie can perform approximately 6,200 requests (~100 seconds) to recover the plaintext PKCE code_verifier. With this, the attacker can exchange a stolen authorization code for the victim's access token. The issue is resolved in versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Potential Impact
Successful exploitation allows an attacker to recover the plaintext PKCE code_verifier from an encrypted cookie by exploiting a padding oracle vulnerability. This enables the attacker to exchange a stolen authorization code for the victim's access token, potentially leading to unauthorized access to protected resources. The vulnerability impacts confidentiality and integrity of OAuth2 authentication flows but does not affect availability.
Mitigation Recommendations
This vulnerability is fixed in envoyproxy envoy versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1. Users should upgrade to one of these versions or later to remediate the issue. No other official remediation or temporary fixes are indicated. Patch status is confirmed by the vendor advisory.
CVE-2026-47775: CWE-209: Generation of Error Message Containing Sensitive Information in envoyproxy envoy
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 v3.1
Score 6.8medium
Affected software
pkg:github/envoyproxy/envoyRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability (CVE-2026-47775) in envoyproxy envoy affects the OAuth2 HTTP filter's encryption and decryption functions that use AES-256-CBC without an authentication tag (no HMAC or AEAD). The /callback endpoint returns distinct HTTP status codes (302 on success, 401 on padding failure), creating a padding oracle side channel. An attacker who obtains the encrypted CodeVerifier cookie can perform approximately 6,200 requests (~100 seconds) to recover the plaintext PKCE code_verifier. With this, the attacker can exchange a stolen authorization code for the victim's access token. The issue is resolved in versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Potential Impact
Successful exploitation allows an attacker to recover the plaintext PKCE code_verifier from an encrypted cookie by exploiting a padding oracle vulnerability. This enables the attacker to exchange a stolen authorization code for the victim's access token, potentially leading to unauthorized access to protected resources. The vulnerability impacts confidentiality and integrity of OAuth2 authentication flows but does not affect availability.
Mitigation Recommendations
This vulnerability is fixed in envoyproxy envoy versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1. Users should upgrade to one of these versions or later to remediate the issue. No other official remediation or temporary fixes are indicated. Patch status is confirmed by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-19T22:36:16.882Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3ec10ed9e07477746fae1b
Added to database: 06/26/2026, 18:12:30 UTC
Last enriched: 07/03/2026, 22:23:41 UTC
Last updated: 08/10/2026, 00:41:16 UTC
Views: 55
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.