Answer in brief
CVE-2026-71478 records a Medium severity (CVSS 6.1) vulnerability in league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes. The current sources do not mark it as known exploited. The current feed maps league/commonmark (composer), thephpleague/commonmark (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 6.1. 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 league/commonmark (composer), thephpleague/commonmark (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| league/commonmarkcomposer | >=1.5.0,<=2.8.3 | 2.9.0 |
| thephpleague/commonmarkgeneric | >= 1.5.0, <= 2.8.3 | Not reported |
Published upstream
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 6, 2026
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-71478 records a Medium severity (CVSS 6.1) vulnerability in league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes. The current sources do not mark it as known exploited. The current feed maps league/commonmark (composer), thephpleague/commonmark (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 6.1. 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 league/commonmark (composer), thephpleague/commonmark (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| league/commonmarkcomposer | >=1.5.0,<=2.8.3 | 2.9.0 |
| thephpleague/commonmarkgeneric | >= 1.5.0, <= 2.8.3 | Not reported |
Published upstream
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 6, 2026
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.
Quoted source text, attributed separately from HOL analysis.