# CVE-2026-56280: Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect

> Read-only API key holders can cancel running native builds by disconnecting from the log stream, bypassing permission checks and disrupting CI/CD workflows.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** GHSA-95g7-xwwx-j737

## What is CVE-2026-56280?

CVE-2026-56280 is a high-severity missing authorization vulnerability in Cap-go capgo, published on 22 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Cap-go before 12.128.2 contains a privilege inversion vulnerability in GET /build/logs/:jobId that allows read-only API key holders to cancel running native builds. The endpoint registers an abort listener on the SSE stream that unconditionally invokes cancelBuildOnDisconnect() using the privileged server-side BUILDER_API_KEY when clients disconnect, bypassing the app.build_native permission check required by the explicit POST /build/cancel/:jobId endpoint. Attackers with read-only API keys can repeatedly disrupt native build operations and CI/CD workflows by opening the log stream and dropping the connection.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-56280?


## How do I fix CVE-2026-56280?

No fix has been published for CVE-2026-56280 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56280 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56280 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56280 and fix it if it is affected.

What it is: CVE-2026-56280 is a high-severity missing authorization vulnerability in Cap-go capgo, published on 22 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56280 exists.

Affected product: Cap-go capgo. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-56280/ (Markdown: https://insights.sbomify.com/CVE-2026-56280/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56280
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56280
- OSV: https://osv.dev/vulnerability/CVE-2026-56280

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56280/
Summaries are generated and may contain mistakes; the official description above is the record.