CVE-2026-41650 fast-xml-parser XMLBuilder: XML Comment and CDATA Injection via Unescaped Delimiters
Attackers can inject malicious XML comments or CDATA sections via unescaped delimiters, potentially leading to XSS or data manipulation in applications using fast-xml-parser.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-41650?
CVE-2026-41650 is a medium-severity cross-site scripting vulnerability in NaturalIntelligence fast-xml-parser, published on 7 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. Prior to version 5.7.0, XMLBuilder does not escape the "-->" sequence in comment content or the "]]>" sequence in CDATA sections when building XML from JavaScript objects. This allows XML injection when user-controlled data flows into comments or CDATA elements, leading to XSS, SOAP injection, or data manipulation. This issue has been patched in version 5.7.0.
Weakness: CWE-91
Which versions are affected by CVE-2026-41650?
2 open source packages ship an affected version, including fast-xml-parser. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
fast-xml-parser npm | All versions | 5.7.0 |
fast-xml-parser npm | All versions | 5.7.0 |
Products include Naturalintelligence Fast-Xml-Parser.
How do I fix CVE-2026-41650?
Upgrade fast-xml-parser to 5.7.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-41650 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41650 exists.
Other vulnerabilities in NaturalIntelligence fast-xml-parser
- CVE-2026-25896 fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
- CVE-2026-33036 fast-xml-parser affected by numeric entity expansion bypassing all entity expansion limits (incomplete fix for CVE-2026-26278)
- CVE-2026-26278 fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit)
- CVE-2026-25128 fast-xml-parser has RangeError DoS Numeric Entities Bug
- CVE-2024-41818 ReDOS at currency parsing fast-xml-parser
Sources
Also known as CLEANSTART-2026-CK33786, CLEANSTART-2026-NG55070, CLSA-2026-1777336754, CLSA-2026-1786525960, DEBIAN-CVE-2026-41650, ECHO-c4c5-a42c-d4a0 and 21 more.