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CVE-2026-58208: NATS Server: MQTT-over-WebSocket Path Can Crash WebSocket-Only JetStream Servers Before MQTT Is Enabled

mediumCVSS 6.8CVE-2026-58208

CSIRTS triage

vendor: NATSproduct: NATS ServerDenial of serviceOther
What
MQTT-over-WebSocket path can crash WebSocket-only JetStream servers before MQTT is enabled.
Who is affected
Deployments of NATS Server with WebSocket-only JetStream are affected.
Urgency
Remediation is medium urgency due to the medium severity of the issue.
Action
Update NATS Server to the latest version.

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Details

Source
Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity
medium — CVSS 6.8
Published
2026-07-02
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58208

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-58208coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for NATS Server

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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