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EnvoyApplication · Envoyproxy

CVE-2021-39162

HIGH · 8.6 CVSS v3.1 Published 2021-09-09
Fix available
A fix is available. Upgrade to 1.18.4 or later.
See remediation →
95/100
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
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, can abnormally terminate if an H/2 GOAWAY and SETTINGS frame are received in the same IO event. This can lead to a DoS in the presence of untrusted *upstream* servers. 0.15.1 contains an upgraded envoy binary with this vulnerability patched. If only trusted upstreams are configured, there is not substantial risk of this condition being triggered.

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 versions prior to 0.15.1 include a vulnerable Envoy binary that can abnormally terminate when receiving an H/2 GOAWAY frame and SETTINGS frame from an upstream server in the same IO event, causing a denial of service condition.

MitigationUpgrade to Pomerium version 0.15.1 or later which contains the patched Envoy binary. If immediate upgrading is not feasible, restrict upstream servers to trusted sources only.

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:< 1.18.4= 1.19.0
PomeriumApplication
Affected:= 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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 check the Pomerium version in your deployment configuration or container image metadata
    Affected if Version is exactly 0.15.0
  2. Check bundled Envoy version
    Locate the Envoy binary bundled with Pomerium (typically in the Pomerium bin directory or container). Run './envoy --version' to identify the Envoy version
    Affected if Envoy version is less than 1.18.4, equals 1.19.0, or is unknown/embedded in Pomerium 0.15.0
  3. Identify HTTP/2 upstream connections
    Review Pomerium configuration files for upstream routes or backend services that use HTTP/2 (h2) protocol. Check for 'protocol: h2' or 'http2: true' settings in route definitions
    Affected if Pomerium proxies HTTP/2 traffic to upstream servers
  4. Verify network exposure to untrusted upstreams
    Review network policies and upstream server definitions. Identify if upstream servers are external or from untrusted networks
    Affected if Upstream servers originate from networks that are not fully trusted or controlled

You are affected if you are running Pomerium version 0.15.0 with bundled Envoy versions below 1.18.4 or exactly 1.19.0, and you have HTTP/2 upstream connections to servers that could send the specific H/2 GOAWAY and SETTINGS frame combination.

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 1.18.4 or later
Fixed in 1.18.4
Interim mitigation

Upgrade to Pomerium version 0.15.1 or later which contains the patched Envoy binary. If immediate upgrading is not feasible, restrict upstream servers to trusted sources only.

Recommended fix High confidence

Pomerium 0.15.1 (or later stable release); Envoy 1.18.4 or 1.19.1+

  1. Upgrade Pomerium from version 0.15.0 to version 0.15.1 or later to obtain the patched Envoy binary
  2. If using Envoy directly, upgrade to version 1.18.4 or 1.19.1 or later
  3. After upgrade, verify the service starts successfully
  4. If only trusted upstreams are configured, this vulnerability has lower exploitability, but upgrading is still recommended

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

Fix this in Envoy Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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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-2021-39162 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