CVE-2021-39206Network attack vector

Authorization bypass via inconsistent request normalization

Published Sep 9, 2021 · Updated Aug 4, 2024

Incorrect authorization in Pomerium 0.11.0 through 0.14.7 and 0.15.0 allows remote attackers to bypass path-based access controls. Its embedded Envoy proxy either includes URI fragments during path matching or sends only the last duplicate-header value for authorization, causing routing and policy evaluation to use different request representations. Exposure requires path-prefix-based policy, and crafted requests can reach resources that the applicable policy was intended to block.

CVSS severity8.6
High
EPSS probability1.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Pomerium 0.11.0 through 0.14.7 and 0.15.0 allows remote attackers to bypass path-based access controls. Its embedded Envoy proxy either includes URI fragments during path matching or sends only the last duplicate-header value for authorization, causing routing and policy evaluation to use different request representations. Exposure requires path-prefix-based policy, and crafted requests can reach resources that the applicable policy was intended to block.

The record

CVE
CVE-2021-39206
Published
Sep 9, 2021
Updated
Aug 4, 2024
Vendor
Pomerium
Product
Pomerium
Classifications
CWE-863, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=>= 0.11.0, < 0.14.8
  2. Affected versionversion=>= 0.15.0, < 0.15.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pomerium · Pomeriumversion=>= 0.11.0, < 0.14.8; version=>= 0.15.0, < 0.15.1

Published CVSS scores

8.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
8.6NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
5.0NISTAV:N/AC:L/Au:N/C:N/I:P/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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