DoS via uncaught RangeError in fast-xml-parser numeric entity processing
In fast-xml-parser versions 5.0.9 through 5.3.3, parsing XML containing out-of-range numeric character references (e.g., � or �) triggers a RangeError during numeric entity processing (e.g., via String.fromCodePoint()), and the exception is not caught. As a result, applications that parse untrusted XML with entity processing enabled can crash due to an uncaught exception. Version 5.3.4 fixes the issue.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
processEntities/htmlEntities unless required); wrap parsing in try/catch (or equivalent error handling) to prevent process termination and return a controlled error; and pre-validate/reject numeric entities outside the Unicode scalar range (0..0x10FFFF) before invoking the parser.Remediation
Patch, then assume compromise.
Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A denial-of-service vulnerability in the fast-xml-parser component where specially crafted XML input (numeric entity handling leading to a RangeError/uncaught exception) can crash or disrupt the service.
A fast-xml-parser vulnerability where specially crafted input can trigger a RangeError (numeric entity handling) leading to remote denial of service (DoS).
A fast-xml-parser vulnerability that can be triggered remotely to cause denial of service via an uncaught exception (RangeError) when processing numeric entities.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.