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MEDIUM severity

CVE-2021-31232 — cortex

MEDIUMFix: cortexproject/cortex#4129

CVE-2021-31232 is a medium-severity (CVSS 5.5) vulnerability in github.com/cortexproject/cortex. A fix is available for github.com/cortexproject/cortex — see the affected versions and patch details below.

Improper input validation in CNCF Cortex

Also known asGHSA-m45g-f45x-vv22GO-2022-0915
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk
0.00%0.29%0.58%0.87%0.1%0.4%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-31232 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐹github.com/cortexproject/cortex

Real-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

The Alertmanager in CNCF Cortex before 1.8.1 has a local file disclosure vulnerability when -experimental.alertmanager.enable-api is used. The HTTP basic auth password_file can be used as an attack vector to send any file content via a webhook. The alertmanager templates can be used as an attack vector to send any file content because the alertmanager can load any text file specified in the templates list.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/cortexproject/cortexall versions1.8.1go get github.com/cortexproject/cortex@v1.8.1

Affected Products

1 product · 1 configurations
Application
cortexlinuxfoundation
< 1.8.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cortexproject/cortex, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/cortexproject/cortex to 1.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-31232 is resolved across your whole dependency graph.

  3. 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

The Alertmanager in CNCF Cortex before 1.8.1 has a local file disclosure vulnerability when -experimental.alertmanager.enable-api is used. The HTTP basic auth password_file can be used as an attack vector to send any file content via a webhook. The alertmanager templates can be used as an attack vector to send any file content because the alertmanager can load any text file specified in the templates list.
O3 Security · Impact-Aware SCA

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CVE-2021-31232: cortex — Fixed in 1.8.1