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EnvoyApplication · Envoyproxy

CVE-2021-39204

HIGH · 7.5 CVSS v3.1 Published 2021-09-09
Fix available
A fix is available. Upgrade to 0.14.8 / 1.17.4 or later.
See remediation →
84/100
Remediation priority · High
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
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.

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

Pomerium, an open-source identity-aware access proxy built on Envoy, contains a vulnerability where Envoy incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset, resulting in a denial of service (DoS) condition.

MitigationUpgrade Pomerium to version 0.14.8 or 0.15.1 which contains the patched Envoy binary with the vulnerability resolved.

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:<= 1.16.4>= 1.17.0, < 1.17.4>= 1.18.0, < 1.18.4= 1.19.0
PomeriumApplication
Affected:< 0.14.8= 0.15.0

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check installed Pomerium version
    Run `pomerium version` or `pomerium --version` to obtain the running Pomerium version number
    Affected if The version is less than 0.14.8, or exactly 0.15.0
  2. Check bundled Envoy version in Pomerium
    Run `pomerium version --json` or examine the Pomerium binary with `pomerium verify` to identify the embedded Envoy version
    Affected if The bundled Envoy version is <= 1.16.4, between 1.17.0 and 1.17.3 inclusive, between 1.18.0 and 1.18.3 inclusive, or exactly 1.19.0
  3. Verify HTTP/2 is enabled in Pomerium config
    Inspect Pomerium configuration file (typically config.yaml or environment variables) for HTTP/2 related settings such as `http_redirect` or any proxy/listener configurations that enable HTTP/2
    Affected if HTTP/2 protocol is enabled on any inbound listener - this is required for the vulnerability to be exploitable
  4. Check for high CPU behavior correlating with HTTP/2 traffic
    Monitor system CPU usage and observe if high utilization coincides with HTTP/2 stream resets or abnormal traffic patterns
    Affected if Unexplained high CPU utilization is observed when HTTP/2 clients reset multiple streams, indicating potential exploitation of this DoS condition

You are affected if Pomerium version is < 0.14.8 or = 0.15.0, OR the bundled Envoy version falls within the vulnerable ranges, AND HTTP/2 is enabled on your Pomerium listeners.

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 0.14.8 / 1.17.4 / 1.18.4 or later
Fixed in 0.14.81.17.41.18.4
Interim mitigation

Upgrade Pomerium to version 0.14.8 or 0.15.1 which contains the patched Envoy binary with the vulnerability resolved.

Recommended fix High confidence

Pomerium >= 0.14.8 or >= 0.15.1 (preferably latest stable)

  1. Identify the currently running Pomerium version using 'pomerium version' or checking the container/部署 manifest
  2. Plan maintenance window as upgrade requires service restart
  3. For containerized deployments: Update the image tag to 'pomerium/pomerium:v0.14.8' or 'pomerium/pomerium:v0.15.1' (or latest stable)
  4. For binary installations: Download the new version from github.com/pomerium/pomerium/releases
  5. Restart Pomerium service to apply the update
  6. Verify the new version is running with 'pomerium version'
  7. Monitor logs for any errors after upgrade

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

Fix this in Envoy Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,950
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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-2021-39204 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