Nats server: Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path
Affects nats-serverSource GCVE Database
Not known to be exploited · CVSS 6.8 Medium · fixed in 2.14.3 : update nats-server when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.14.3
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10nats-serverpkg:deb/ubuntu/nats-server?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu Pro 26.04 LTSnats-serverpkg:deb/ubuntu/nats-server?arch=source&distro=esm-apps/resoluteOther threats | Affected
| Fixed in– |
Ubuntu 25.10nats-serverpkg:deb/ubuntu/nats-server?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSnats-serverpkg:deb/ubuntu/nats-server?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade NATS Server to version 2.14.3 or 2.12.12 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated.
Description
NATS Server versions prior to 2.14.3 and 2.12.12 contain a vulnerability where a WebSocket listener incorrectly routes MQTT-over-WebSocket requests into MQTT handling even if MQTT is not configured. This flaw allows an unauthenticated client to crash the server process by triggering an uninitialized MQTT state. The issue is resolved in versions 2.14.3 and 2.12.12.
References
- ubuntu.com/security/CVE-2026-58208 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-58208 (opens in a new tab)
- github.com/nats-io/nats-server/security/advisories/GHSA-p957-7v2w-g93g (opens in a new tab)
- github.com/nats-io/nats-server/commit/73b3dd9a5ea0fa7bf08b702338676355b29b5fb4 (opens in a new tab)
- github.com/nats-io/nats-server/commit/837536b98b3a9280b993282155ff2bdd3ca38c30 (opens in a new tab)
- github.com/nats-io/nats-server/releases/tag/v2.12.12 (opens in a new tab)
- github.com/nats-io/nats-server/releases/tag/v2.14.3 (opens in a new tab)