CVE-2026-47775Public exploitNetwork attack vector

Access token theft via CBC padding oracle

Published Jun 26, 2026 · Updated Jun 26, 2026

Padding oracle exposure in Envoy's OAuth2 HTTP filter allows remote attackers to recover PKCE verifiers and obtain access tokens. The filter encrypts CodeVerifier cookies with unauthenticated AES-256-CBC, and its callback distinguishes valid decryption with HTTP 302 from padding failure with HTTP 401. Exploitation requires a victim's encrypted cookie and authorization code, user initiation of an OAuth2 flow, and roughly 6,200 requests within the cookie lifetime.

CVSS severity6.8
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Padding oracle exposure in Envoy's OAuth2 HTTP filter allows remote attackers to recover PKCE verifiers and obtain access tokens. The filter encrypts CodeVerifier cookies with unauthenticated AES-256-CBC, and its callback distinguishes valid decryption with HTTP 302 from padding failure with HTTP 401. Exploitation requires a victim's encrypted cookie and authorization code, user initiation of an OAuth2 flow, and roughly 6,200 requests within the cookie lifetime.

The record

CVE
CVE-2026-47775
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-209, CWE-327, T1528
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.35.11
  2. Affected versionversion=>= 1.36.0, < 1.36.7
  3. Affected versionversion=>= 1.37.0, < 1.37.3
  4. Affected versionversion=>= 1.38.0, < 1.38.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.35.11; version=>= 1.36.0, < 1.36.7; version=>= 1.37.0, < 1.37.3; version=>= 1.38.0, < 1.38.1

Published CVSS scores

6.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-209Generation of Error Message Containing Sensitive Information
CWE-327Use of a Broken or Risky Cryptographic Algorithm
T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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