Incorrect Authorization with specially crafted requests

Description

Envoy, which Pomerium is based on, contains two authorization related vulnerabilities:

  • CVE-2021-32777: incorrectly transform a URL containing a #fragment element, causing a mismatch in path-prefix based authorization decisions.
  • CVE-2021-32779: incorrectly handle duplicate headers, dropping all but the last. This may lead to incorrect routing or authorization policy decisions.

Impact

With specially crafted requests, incorrect authorization or routing decisions may be made by Pomerium.

Patches

Pomerium v0.14.8 and v0.15.1 contain an upgraded envoy binary with these vulnerabilities patched.

Workarounds

  • This issue can only be triggered when using path prefix based policy. Removing any such policies should provide mitigation.

References

envoy GSA CVE-2021-32777
envoy GSA CVE-2021-32779
envoy announcement

For more information

If you have any questions or comments about this advisory:
* Open an issue in pomerium/pomerium
* Email us at [email protected]

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
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Repository advisory
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Source code
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Published (advisory)
2021-09-10 17:54:25 UTC
Updated
2023-02-01 05:06:06 UTC
GitHub reviewed
2021-09-10 16:40:43 UTC
NVD published
2021-09-09

EPSS Score

Score Percentile
0.16% 37.47%

CVSS Scores

Base score Version Severity Vector
8.6 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-863 Incorrect Authorization

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/pomerium/pomerium >= 0.11.0, < 0.14.8 0.14.8
go github.com/pomerium/pomerium = 0.15.0 0.15.1

References

cvelogic Threat Intelligence