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Arbitrary redirects under /new endpoint

Moderate severity GitHub Reviewed Published May 18, 2021 in prometheus/prometheus • Updated Jun 24, 2025

Package

gomod github.com/prometheus/prometheus (Go)

Affected versions

>= 2.23.0, < 2.26.1
= 2.27.0
> 0.0.0-20201116123734-de1c1243f4dd, < 0.0.0-20210518124745-db7f0bcec27b

Patched versions

2.26.1
2.27.1
0.0.0-20210518124745-db7f0bcec27b

Description

Impact

In 2.23.0, Prometheus changed its default UI to the New ui. To ensure a seamless transition, the URL's prefixed by /new redirect to /.
Due to a bug in the code, it is possible for an attacker to craft an URL that can redirect to any other URL, in the /new endpoint.

If a user visits a prometheus server with a specially crafted address (e.g.: http://127.0.0.1:9090/new/new<url>), they can be redirected to an arbitrary URL.

e.g. if a user visits http://127.0.0.1:9090/new/newhttp://www.google.com/, they will be redirected to http://google.com.

Patches

The issue will be patched in 2.26.1 and 2.27.1 releases.
In 2.28.0, the /new endpoint will be removed completely.

Workarounds

The workaround is to disable access to /new via a reverse proxy in front of Prometheus.

Note: Users who use a --web.external-url= flag with a path (e.g. --web.external-url=http://example.com/prometheus) are not affected.

For more information

If you have any questions or comments about this advisory, please use our community channels (https://prometheus.io/community).
Our security policy is available at https://prometheus.io/docs/operating/security/

References

@csmarchbanks csmarchbanks published to prometheus/prometheus May 18, 2021
Reviewed May 19, 2021
Published by the National Vulnerability Database May 19, 2021
Published to the GitHub Advisory Database Feb 15, 2022
Last updated Jun 24, 2025

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
Low
Privileges required
None
User interaction
Required
Scope
Changed
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:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(99th percentile)

Weaknesses

URL Redirection to Untrusted Site ('Open Redirect')

A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. Learn more on MITRE.

CVE ID

CVE-2021-29622

GHSA ID

GHSA-vx57-7f4q-fpc7

Source code

No known source code

Credits

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