# CVE-2026-44300

## Summary

- **CVE ID:** CVE-2026-44300
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-20, CWE-309
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## Description

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

## Affected Products

- opencost — opencost (< 1.121.0)

## References

- [CNA](https://github.com/opencost/opencost/security/advisories/GHSA-wmj8-9953-vff5)
- [CNA](https://github.com/opencost/opencost/pull/3651)
- [CNA](https://github.com/opencost/opencost/pull/3910)
- [CNA](https://github.com/opencost/opencost/commit/69430e7f627b3e62c8999312c06949267fab813a)
- [CNA](https://github.com/opencost/opencost/commit/a49a25bc2e0d6e220a131a4dc58f38ebe6ae851b)
- [CNA](https://github.com/opencost/opencost/releases/tag/v1.120.0)
- [CNA](https://github.com/opencost/opencost/releases/tag/v1.121.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.41%
- **EPSS Percentile:** 35.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._