# step-ca has Unauthenticated Certificate Issuance via SCEP UpdateReq (MessageType=18)

Advisory record · `GHSA-q4r8-xm5f-56gw`

- **Identifiers:** `GHSA-q4r8-xm5f-56gw` · `CVE-2026-30836` · `GO-2026-4775`
- **State:** Confirmed
- **Severity:** CVSS 10.0 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-287](https://cwe.mitre.org/data/definitions/287.html) · [CWE-295](https://cwe.mitre.org/data/definitions/295.html)
- **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md) · [Weak cryptography or TLS](https://agentprime.io/advisories/tag/weak-crypto.md)
- **Published:** 19 Mar 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Mar 2026, 16:27 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 10.0: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `github.com/smallstep/certificates` (Go): affected `<0.30.0`; fixed in `0.30.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Step CA (Go package github.com/smallstep/certificates) versions before 0.30.0 let an attacker make a SCEP provisioner issue certificates without the SCEP authorization checks. The flaw is that unsupported but valid SCEP message types skip authorization logic. Upgrade to version 0.30.0 or newer; if you cannot, temporarily disable or remove SCEP provisioners, or restrict them to trusted clients.

Written 1 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 10.0 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0032, the 25th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:14 UTC: First seen by agentprime
- 31 Oct 2026, 14:14 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-q4r8-xm5f-56gw)

## Sources

- [GitHub Advisory Database: GHSA-q4r8-xm5f-56gw](https://github.com/advisories/GHSA-q4r8-xm5f-56gw)
- [OSV: GHSA-q4r8-xm5f-56gw](https://osv.dev/vulnerability/GHSA-q4r8-xm5f-56gw)
- <https://github.com/smallstep/certificates/security/advisories/GHSA-q4r8-xm5f-56gw>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-30836>
- <https://github.com/smallstep/certificates/commit/e6da031d5125cfd99fe9a26f74bb41e4dacca4ef>
- <https://github.com/smallstep/certificates>
- <https://github.com/smallstep/certificates/releases/tag/v0.30.0-rc7>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-q4r8-xm5f-56gw>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-q4r8-xm5f-56gw/>. Everything for agents: <https://agentprime.io/llms.txt>.