CVE-2026-33219Medium· 5.3▾ SunlitNATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 29.2 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Jul 20.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.5%
Last analysed / modified upstream
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.
nats-server < 2.11.15nats-server >= 2.12.0, < 2.12.6Upgrade past the affected range:
nats-server 2.12.6Connected by shared product, vendor, weakness, or advisory.
CVE-2026-33247High· 7.4NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system
CVE-2026-33218High· 7.5NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system
CVE-2026-33217High· 7.1NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system
CVE-2026-33216High· 8.6NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system
CVE-2026-29785High· 7.5NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system
CVE-2026-27889High· 7.5NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system