Resource exhaustion in nats-server - #VU166208
Published: November 13, 2026
Vulnerability identifier: #VU166208
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service through excessive memory consumption, stalled message delivery, or server process termination.
The vulnerability exists due to uncontrolled memory allocation in the nats-server queue subscription matching logic when resolving subscriptions using weights supplied by route or leafnode peers. A remote attacker can supply a crafted queue subscription weight through an accepted route or leafnode peer to exhaust server memory and disrupt message delivery.
Affected software
nats-server
Remediation
Install security update from vendor's website.
nats-server - addressed in versions 2.14.9, 2.15.2