Inefficient Algorithmic Complexity in fast-xml-parser - #VU159256
Published: November 4, 2026
Vulnerability identifier: #VU159256
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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 through excessive CPU consumption.
The vulnerability exists due to inefficient algorithmic complexity in fast-xml-parser's readStopNodeData() function when processing unterminated tags with the non-default stopNodes option enabled. A remote attacker can submit crafted XML constructed as '<stop>' + '<a '.repeat(n), with stopNodes configured to match the root element and no subsequent '>' character, to trigger repeated scans of the remaining input and quadratic CPU consumption before the parser throws an error.
Affected software
fast-xml-parser
Remediation
Install security update from vendor's website.
fast-xml-parser - update to 5.12.0