Resource exhaustion in Nats-io Nats-server
CVE-2026-27571
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The WebSockets handling of NATS messages handles compressed messages via the WebSockets negotiated compression. Prior to versions 2.11.2 and 2…
EPSS: 0.000 (10.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Nats-io Nats-server — versions < 2.11.12, >= 2.12.0-RC.1, < 2.12.3
Weakness classification (CWE)
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-qrvq-68c2-7grw (x_refsource_CONFIRM)
- https://github.com/nats-io/nats-server/commit/f77fb7c4535e6727cc1a2899cd8e6bbdd8ba2017 (x_refsource_MISC)
- https://github.com/nats-io/nats-server/releases/tag/v2.11.12 (x_refsource_MISC)
- https://github.com/nats-io/nats-server/releases/tag/v2.12.3 (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-27571?
- CVE-2026-27571 is a medium-severity vulnerability in Nats-io Nats-server, classified under Improper Handling of Highly Compressed Data (Data Amplification). CVSS score: 5.9/10. Published 2026-02-24.
- How severe is CVE-2026-27571?
- Medium severity. CVSS v3 base score is 5.9 out of 10.