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CVE-2026-47775

Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption

6.8 MediumFix available

CVE-2026-47775 is a medium vulnerability (CVSS 6.8) in Envoyproxy Envoy, published June 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in envoy 1.35.11.

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.22%Unchanged since Jun 27, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.8

Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption

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.

Record
CVE-2026-47775
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-209, CWE-327
Updated
2026-11-02
EUVDEUVD-2026-39817 6.8

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.

Record
EUVD-2026-39817
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-02
NVD 6.8

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.

Record
CVE-2026-47775
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-209, CWE-327
Updated
2026-11-02
OSV 6.8

Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption

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.

Record
CVE-2026-47775
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-209, CWE-327
Updated
2026-11-02
OSVBIT-envoy-2026-47775 No score

Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption

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.

Record
BIT-envoy-2026-47775
Updated
2026-11-02
OSVopenSUSE-SU-2026:11141-1 No score

istioctl-1.30.2-1.1 on GA media

These are all security issues fixed in the istioctl-1.30.2-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11141-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
envoy
Bitnami
before 1.35.11, 1.36.0 up to 1.36.7, 1.37.0 up to 1.37.3, 1.38.0 up to 1.38.1
1.35.111.36.71.37.31.38.1
istioctl
openSUSE:Tumbleweed
before 1.30.2-1.1
1.30.2-1.1

History

History
WhenChangedSources
2026-11-02aliases, publishedEUVD
2026-11-02createdCVE List, NVD, OSV

References

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