# CVE-2026-44300: OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

> Unauthenticated attackers can overwrite GCP service account credentials in OpenCost, potentially hijacking cloud cost collection or causing service disruption.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-wmj8-9953-vff5, GO-2026-5974

## What is CVE-2026-44300?

CVE-2026-44300 is a high-severity missing authorization vulnerability in opencost, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-309 (Use of Password System for Primary Authentication), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-44300?

3 open source packages ship an affected version, including github.com/opencost/opencost.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/opencost/opencost` | Go | All versions | 1.119.1 |
| `github.com/opencost/opencost` | Go | All versions | 1.119.1 |
| `github.com/opencost/opencost` | Go | All versions | 1.119.1 |

## How do I fix CVE-2026-44300?

Upgrade github.com/opencost/opencost to 1.119.1 or later.

## Is CVE-2026-44300 being exploited?

There is no known exploitation of CVE-2026-44300 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44300 and fix it if it is affected.

What it is: CVE-2026-44300 is a high-severity missing authorization vulnerability in opencost, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-44300 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/opencost/opencost (Go): affected all versions; fixed in 1.119.1
- github.com/opencost/opencost (Go): affected all versions; fixed in 1.119.1
- github.com/opencost/opencost (Go): affected all versions; fixed in 1.119.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-44300/ (Markdown: https://insights.sbomify.com/CVE-2026-44300/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44300
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44300
- OSV: https://osv.dev/vulnerability/CVE-2026-44300

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44300/
Summaries are generated and may contain mistakes; the official description above is the record.