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EnvoyApplication · Envoyproxy

CVE-2023-35941

CRITICAL · 9.8 CVSS v3.1 Published 2023-07-25
Fix available
A fix is available. Upgrade to 1.23.12 / 1.24.10 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, a malicious client is able to construct credentials with permanent validity in some specific scenarios. This is caused by the some rare scenarios in which HMAC payload can be always valid in OAuth2 filter's check. Versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12 have a fix for this issue. As a workaround, avoid wildcards/prefix domain wildcards in the host's domain configuration.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Envoy's OAuth2 filter contains a vulnerability where a malicious client can construct credentials with permanent validity. This occurs when HMAC payload validation always returns true in specific rare scenarios, which is triggered by certain wildcard or prefix domain configurations in the host's domain settings.

MitigationPrimary mitigation is to upgrade Envoy to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, or 1.23.12 or later. As a workaround, avoid using wildcards or prefix domain wildcards in the host's domain configuration.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
EnvoyApplication
Affected:>= 1.23.0, < 1.23.12>= 1.24.0, < 1.24.10>= 1.25.0, < 1.25.9>= 1.26.0, < 1.26.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Determine Envoy version
    Run 'envoy --version' or check the Envoy binary/version being used
    Affected if Version is 1.23.0-1.23.11, 1.24.0-1.24.9, 1.25.0-1.25.8, or 1.26.0-1.26.3 (within the affected ranges)
  2. Verify OAuth2 filter is in use
    Inspect Envoy configuration (static_resources.filters or dynamic_resources) for 'envoy.filters.http.oauth2' filter type, or review the deployed filter chain
    Affected if The OAuth2 filter is deployed and configured in the filter chain
  3. Inspect OAuth2 domain configuration for wildcards
    Review the OAuth2 filter configuration, specifically the 'allowed_domains' or 'domains' setting under the OAuth2 filter configuration. Look for domain strings containing '*' (wildcard) or strings starting with '*.' (prefix wildcard)
    Affected if The domain configuration uses wildcard patterns such as '*.example.com' or similar prefix wildcards that could match arbitrary subdomains

User is affected if running an affected Envoy version with the OAuth2 filter enabled and using wildcard or prefix domain configurations in the domain settings.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.23.12 / 1.24.10 / 1.25.9 or later
Fixed in 1.23.121.24.101.25.9
Interim mitigation

Primary mitigation is to upgrade Envoy to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, or 1.23.12 or later. As a workaround, avoid using wildcards or prefix domain wildcards in the host's domain configuration.

Recommended fix High confidence

1.27.0 (or latest stable 1.27.x/1.28.x)

  1. 1. Identify the currently deployed Envoy version using `envoy --version` or checking your deployment configuration
  2. 2. Determine which version branch you are currently on (1.23.x, 1.24.x, 1.25.x, or 1.26.x)
  3. 3. Upgrade Envoy to the corresponding fixed version for your branch: for 1.23.x upgrade to 1.23.12, for 1.24.x upgrade to 1.24.10, for 1.25.x upgrade to 1.25.9, for 1.26.x upgrade to 1.26.4
  4. 4. Alternatively, upgrade to 1.27.0 or later which contains the fix for all affected versions
  5. 5. After upgrading, verify the OAuth2 filter is functioning correctly and validate that HMAC validation is properly enforced
  6. 6. Test the OAuth2 authentication flow to ensure credentials no longer have permanent validity

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Envoy Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-35941 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data