Inefficient Algorithmic Complexity in msgpack5 - #VU152778
Published: September 29, 2026
Vulnerability identifier: #VU152778
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: N/A
CWE-ID: CWE-407
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient algorithmic complexity in the streaming decoder when processing a valid MessagePack value split across many small chunks. A remote attacker can split one valid MessagePack value across many small chunks to cause a denial of service.
The quadratic CPU usage can block the event loop.
Affected software
msgpack5
Remediation
Install security update from vendor's website.
msgpack5 - update to 6.1.0