DEV Community

CVE Reports
CVE Reports

Posted on • Originally published at cvereports.com

CVE-2026-24117: The Key to the Kingdom: SSRF in Sigstore Rekor

#security #cve #cybersecurity

The Key to the Kingdom: SSRF in Sigstore Rekor

Vulnerability ID: CVE-2026-24117
CVSS Score: 9.1
Published: 2026-01-22

A 'convenient' feature in Sigstore's Rekor transparency log turned into a classic Server-Side Request Forgery hole. By allowing the server to fetch public keys via URL, developers inadvertently handed attackers a flashlight to explore their internal networks.

TL;DR

Rekor's /api/v1/index/retrieve endpoint allowed users to submit a URL for the server to fetch a public key. This resulted in a Blind SSRF vulnerability. Attackers could force the Rekor server to make requests to internal resources (like AWS metadata or Kubernetes APIs). The fix was a breaking change: the server no longer fetches URLs; the client must download the key first and send the bytes.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-918
  • Vulnerability Type: Blind SSRF
  • CVSS (Estimated): 9.1 (Critical)
  • Attack Vector: Network
  • Privileges Required: None
  • Breaking Change: Yes (API Field Removed)

Affected Systems

  • Sigstore Rekor Server < v1.5.0
  • Kubernetes clusters hosting vulnerable Rekor instances
  • Cloud environments (AWS/GCP) exposing metadata services to Rekor pods
  • sigstore/rekor: < 1.5.0 (Fixed in: 1.5.0)

Code Analysis

Commit: 60ef2bc

feat: remove url from search index public key to prevent SSRF

-        url:
-          type: string
-          format: strfmt
Enter fullscreen mode Exit fullscreen mode

Exploit Details

  • Manual: Payload construction involves simple JSON manipulation of the publicKey.url field.

Mitigation Strategies

  • Disable the Retrieve API endpoint
  • Network Segmentation (Egress filtering)
  • Upgrade to fixed version

Remediation Steps:

  1. Upgrade Sigstore Rekor to version v1.5.0 or later.
  2. If immediate upgrade is not possible, start the Rekor server with the flag --enable_retrieve_api=false to disable the vulnerable endpoint.
  3. Audit logs for requests to /api/v1/index/retrieve with suspicious URLs in the payload.

References

Read the full report for CVE-2026-24117 on our website for more details including interactive diagrams and full exploit analysis.

Top comments (0)