Answer in brief
CVE-2026-26278 records a High severity (CVSS 7.5) vulnerability in fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit). The current sources do not mark it as known exploited. The current feed maps NaturalIntelligence/fast-xml-parser (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-26278 records a High severity (CVSS 7.5) vulnerability in fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit). The current sources do not mark it as known exploited. The current feed maps NaturalIntelligence/fast-xml-parser (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps NaturalIntelligence/fast-xml-parser (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| NaturalIntelligence/fast-xml-parsergeneric | >= 5.0.0, < 5.3.6 || >= 4.1.3, < 4.5.4 | Not reported |
Published upstream
Feb 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.
Quoted source text, attributed separately from HOL analysis.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps NaturalIntelligence/fast-xml-parser (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| NaturalIntelligence/fast-xml-parsergeneric | >= 5.0.0, < 5.3.6 || >= 4.1.3, < 4.5.4 | Not reported |
Published upstream
Feb 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.
Quoted source text, attributed separately from HOL analysis.