Prometheus vulnerable to basic authentication bypassGHSA-4v48-4q5m-8vx4
HIGHFix: prometheus/prometheus@31a2db3GHSA-4v48-4q5m-8vx4 is a high-severity (CVSS 7.2) vulnerability in github.com/prometheus/prometheus. A fix is available for github.com/prometheus/prometheus — see the affected versions and patch details below.
Real-World Exposure
github.com/prometheus/prometheus🐹github.com/prometheus/prometheus🐹github.com/prometheus/prometheus/v2🐹github.com/prometheus/prometheus/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Prometheus can be secured by a web.yml file that specifies usernames and hashed passwords for basic authentication.
Passwords are hashed with bcrypt, which means that even if you have access to the hash, it is very hard to find the original password back.
However, a flaw in the way this mechanism was implemented in the exporter toolkit makes it possible with people who know the hashed password to authenticate against Prometheus.
A request can be forged by an attacker to poison the internal cache used to cache the computation of hashes and make subsequent requests successful. This cache is used in both happy and unhappy scenarios in order to limit side channel attacks that could tell an attacker if a user is present in the file or not.
Patches
Prometheus 2.37.4 (LTS) and 2.40.4 have been released to address this issue.
Workarounds
There is no workaround but attacker must have access to the hashed password, stored in disk, to bypass the authentication.
Credit
We want to thank Lei Wan for reporting this security issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/prometheus/prometheus | ≥ 2.24.1&&< 2.37.4 | 2.37.4go get github.com/prometheus/prometheus@v2.37.4 |
| 🐹Go | github.com/prometheus/prometheus | ≥ 2.38.0&&< 2.40.4 | 2.40.4go get github.com/prometheus/prometheus@v2.40.4 |
| 🐹Go | github.com/prometheus/prometheus/v2 | ≥ 2.24.1&&< 2.37.4 | 2.37.4go get github.com/prometheus/prometheus/v2@v2.37.4 |
| 🐹Go | github.com/prometheus/prometheus/v2 | ≥ 2.38.0&&< 2.40.4 | 2.40.4go get github.com/prometheus/prometheus/v2@v2.40.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/prometheus/prometheus, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/prometheus/prometheus to 2.37.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4v48-4q5m-8vx4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-4v48-4q5m-8vx4 in your dependencies?
Find it across Go, including transitive dependencies.