Uncontrolled Memory Allocation in nats-server - #VU166207
Published: November 13, 2026
Vulnerability identifier: #VU166207
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-789
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service by exhausting server memory or stalling message delivery.
The vulnerability exists due to memory allocation with an excessive size value in the NATS Server subscription-matching functionality when matching messages using queue subscription weights advertised by peers. A remote user can advertise a specially crafted queue subscription weight over a route or leafnode connection accepted by the server to trigger excessive memory allocation while a subscription-list lock is held, stalling message delivery or terminating the server through memory exhaustion.
Affected software
nats-server
Remediation
Install security update from vendor's website.
nats-server - addressed in versions 2.14.9, 2.15.2