CVE-2026-59387: Access Control Flaw (CVSS 8.8)

Description

The Nginx routing configuration for Cloud Controller blocks unauthenticated access to /internal/v4/ and /internal/v5/ endpoints but omits an equivalent deny rule for /internal/v3/. As a result, the staging callback endpoints /internal/v3/staging/:guid/droplet_completed and /internal/v3/staging/:guid/build_completed are reachable from the public API listener without OAuth or mutual TLS. An attacker with a valid build or droplet GUID can submit a forged staging callback, transition a droplet to STAGED, and persist arbitrary process metadata and sidecar data with no associated package or actor. A SpaceAuditor can enumerate GUIDs without write permissions, making this an effective privilege escalation beyond the intended role boundary.

Is your site exposed to CVE-2026-59387?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-284 CWE-284

References

Other References

https://www.cloudfoundry.org/blog/cve-2026-59387-broken-access-control-restriction-in-cloud-controller-api/

Frequently Asked Questions

What is CVE-2026-59387? +

The Nginx routing configuration for Cloud Controller blocks unauthenticated access to /internal/v4/ and /internal/v5/ endpoints but omits an equivalent deny rule for /internal/v3/. As a result, the staging callback endpoints /internal/v3/staging/:guid/droplet_completed and /internal/v3/staging/:guid/build_completed are reachable from the public API listener without OAuth or mutual TLS. An attacker with a valid build or droplet GUID can submit a forged staging callback, transition a droplet to STAGED, and persist arbitrary process metadata and sidecar data with no associated package or actor. A SpaceAuditor can enumerate GUIDs without write permissions, making this an effective privilege escalation beyond the intended role boundary. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-59387? +

CVE-2026-59387 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-59387? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-35402

mcp-neo4j-cypher is an MCP server for executing Cypher queries against Neo4j databases. In versions prior to 0.6.0, the read_only mode …

CVE-2026-40866

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-40865

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-40874

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, no administrator verification takes …

CVE-2026-54533

vantage6 is an open-source infrastructure for privacy preserving analysis. Prior to version 5.0.0, malicious algorithms can potentially access other algorithms …

CVE-2026-77371

Redash is a package for data visualization and sharing. From 26.0.0 until 26.9.0, the DuckDB query runner's _connect() path in …