Input validation error in nats-server - CVE-2026-27571
Published: February 24, 2026
Vulnerability identifier: #VU123157
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-27571
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient validation of user-supplied input when WebSockets handling the NATS messages. A remote attacker can use a compression bomb to cause excessive memory consumption and perform a denial of service (DoS) attack.
Affected software
nats-server
How to mitigate CVE-2026-27571
Install updates from vendor's website.
nats-server - addressed in versions 2.11.12, 2.12.3