Security Digest · Vulnerability record
CVE-2026-30836: step-ca has Unauthenticated Certificate Issuance via SCEP UpdateReq (MessageType=18)
Step CA is an online certificate authority for secure, automated certificate management for DevOps.
CVSS 10.0 Critical EPSS 0.3% · p24
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.3%, percentile 24: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 24% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
github.com/smallstep/certificates(Go) < 0.30.0, fixed in 0.30.0. Check your lockfile, including transitive dependencies.
What it is
Step CA is an online certificate authority for secure, automated certificate management for DevOps. Versions 0.30.0-rc6 and below do not safeguard against unauthenticated certificate issuance through the SCEP UpdateReq. This issue has been fixed in version 0.30.0.
From the GitHub advisory
Summary
An attacker can force a Step CA SCEP provisioner to create certificates without completing certain protocol authorization checks.
Details
SCEP requests carry a message type. On receipt of a SCEP request, Step CA starts processing it by parsing its contents. Message types that were considered valid, but not explicitly supported in Step CA, would result in getting parsed successfully. While processing the parsed SCEP message, authorization logic would be skipped for the non-supported message types.
As a result, the request would be treated as authorized, bypassing the authorization checks normally enforced as part of the SCEP protocol and its implementation in Step CA.
Weakness type: CWE-287, CWE-295.
Product: github.com/smallstep/certificates (Go) · Assigned by: GitHub_M · Published: 2026-03-19
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | github.com/smallstep/certificates | < 0.30.0 | 0.30.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| smallstep | certificates | < 0.30.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 10 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N |
| GitHub | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.32% probability of exploitation activity in the next 30 days; percentile 24.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-q4r8-xm5f-56gw published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-q4r8-xm5f-56gw github.com
- CVE.org record CVE-2026-30836 cve.org
- NVD entry CVE-2026-30836 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com