CVE-2026-26190: Milvus Unauthenticated REST API Access on Metrics Port 9091
Milvus, an open-source vector database, exposes TCP port 9091 by default and registers its full REST API on the metrics and management port without authentication. A debug expression endpoint also relies on a weak, predictable default token, which the record links to a default etcd.rootPath value. The record rates this CWE-306 issue critical (CVSS 9.8), and it is fixed in 2.5.27 and 2.6.10.
Overview
Milvus is an open-source vector database built for generative AI applications. According to the GitHub advisory referenced in the record, versions before 2.5.27 and from 2.6.0 before 2.6.10 expose TCP port 9091 by default, and the full REST API is served on the metrics and management port without authentication. The record classifies the weakness as CWE-306 (Missing Authentication for Critical Function).
Impact
- The record states that unauthenticated access allows business operations, including data manipulation and credential management.
- A debug expression endpoint uses a default token that the record describes as weak and predictable, derived from etcd.rootPath (default: by-dev), which the record says enables arbitrary expression evaluation.
- The NVD-linked CVSS 9.8 vector (network, low complexity, no privileges, no user interaction, high confidentiality, integrity and availability impact) indicates a severe potential outcome.
Affected products and versions
- Milvus (Milvus Milvus): before 2.5.27, and from 2.6.0 before 2.6.10.
- Milvus-io Milvus: listed in the record with the same ranges, before 2.5.27 and from 2.6.0 before 2.6.10.
Exploitation status
- The CISA KEV catalog does not list this CVE in the record, so no confirmed active exploitation is recorded in the sources consulted.
- The SSVC data in the record marks exploitation as proof of concept and automatable as yes. This is a risk indicator, not confirmation of attacks in the wild.
Remediation and mitigation
- Upgrade Milvus to 2.5.27 or 2.6.10 (or a later release in the applicable line), as referenced by the vendor release notes.
- Consult the vendor advisory for the mitigation guidance it provides; the record does not include its full text.
- Until patching is complete, restrict network access to the metrics and management port so that only trusted administrative hosts can reach it, and avoid exposing it to untrusted networks.
Detection guidance
- Inventory Milvus deployments and identify versions below the fixed releases.
- Review network exposure of port 9091 and flag any unexpected reachable instances.
- Review access logs on the metrics and management interfaces for requests from unexpected sources.
Limitations of the available information
- The record does not provide full technical details beyond the description, and it does not confirm the exact behavior of the vendor mitigation.
- The EPSS value is a statistical estimate, not evidence of exploitation.
- Whether a particular deployment is affected depends on its configuration, including whether port 9091 is reachable.
Frequently asked questions
What is the core problem in CVE-2026-26190?
According to the record, Milvus serves its full REST API on the metrics and management port without authentication, so anyone who can reach that port may access business operations.
Which versions are fixed?
The record states the issue is fixed in 2.5.27 and 2.6.10. Affected ranges are before 2.5.27 and from 2.6.0 before 2.6.10.
Is this vulnerability known to be exploited in the wild?
The CISA KEV catalog does not list it in the record, so no confirmed active exploitation appears in the sources consulted. The SSVC data indicates a proof of concept exists.
What should administrators do first?
Upgrade to a fixed version and, until then, restrict network access to the metrics and management port to trusted administrative hosts.
This analysis was drafted with AI assistance from verified source data and automatically checked against it.