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Header dropping in traefik

Moderate severity GitHub Reviewed Published Aug 3, 2021 in traefik/traefik • Updated Feb 1, 2023

Package

gomod github.com/traefik/traefik (Go)

Affected versions

<= 1.7.30

Patched versions

None
gomod github.com/traefik/traefik/v2 (Go)
< 2.4.13
2.4.13

Description

Impact

There exists a potential header vulnerability in Traefik's handling of the Connection header. Active exploitation of this issue is unlikely, as it requires that a removed header would lead to a privilege escalation, however, the Traefik team has addressed this issue to prevent any potential abuse.

Details

If you have a chain of Traefik middlewares, and one of them sets a request header Important-Security-Header, then sending a request with the following Connection header will cause it to be removed before the request was sent:

curl 'https://example.com' -H "Connection: Important-Security-Header" -0

In this case, the backend does not see the request header Important-Security-Header.

Patches

Traefik v2.4.x: https://github.com/traefik/traefik/releases/tag/v2.4.13

Workarounds

No.

For more information

If you have any questions or comments about this advisory, open an issue.

References

@emilevauge emilevauge published to traefik/traefik Aug 3, 2021
Published by the National Vulnerability Database Aug 3, 2021
Reviewed Aug 4, 2021
Published to the GitHub Advisory Database Aug 5, 2021
Last updated Feb 1, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS score

0.245%
(65th percentile)

Weaknesses

CVE ID

CVE-2021-32813

GHSA ID

GHSA-m697-4v8f-55qg

Source code

github.com/traefik/traefik
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