Maestro: maestro: grpc broker has no auth interceptor and client mtls is optional

published 2026-10-05 34 d ago modified 2026-10-06 34 d ago also EUVD-2026-92711

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits: 0; none known

A flaw was found in the maestro gRPC broker. This vulnerability allows a remote attacker, with a valid client certificate, to bypass authentication. This bypass enables the attacker to subscribe to other consumers' event streams, leading to unauthorized information disclosure, or to publish forged agent status, which can compromise data integrity.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-71297 updated 2026-10-05 cvss 5.4

maestro: maestro: gRPC broker has no auth interceptor and client mTLS is optional

Red Hat Multicluster Engine for Kubernetes multicluster-engine/maestro-rhel9, multicluster-engine/cloudevents-conductor-rhel9
affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 34 d ago (2026-10-06)

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Affected products

Red Hat Multicluster Engine for Kubernetes

Classification

Weakness

CWE-306 Missing Authentication for Critical Functionality

References

access.redhat.com /security/cve/CVE-2026-71297
vdb-entry
bugzilla.redhat.com /show_bug.cgi?id=2511518
issue-tracking

Sources

CVE List CVE-2026-71297
NVD CVE-2026-71297

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary