6.1

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2023-39318

CVE-2023-39318: The html/template package does not properly handle HTML-like "" comment tokens, nor hashbang "#!"...

The html/template package does not properly handle HTML-like "" comment tokens, nor hashbang "#!" comment tokens, in <script> contexts. This may cause the template parser to improperly interpret the contents of <script> contexts, causing actions to be improperly escaped. This may be leveraged to perform an XSS attack.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2023-39318

CVE-2023-39318:

6.1

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

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Root Cause Analysis

The vulnerability lies in the html/template package's parser, specifically how it handles HTML-like comments () and hashbang comments (#!) within <script> contexts. The provided patch directly addresses this by modifying the state machine and transition functions within the package.

New States: The patch introduces stateJSHTMLOpenCmt and stateJSHTMLCloseCmt in context.go to represent these comment types within JavaScript.
Modified Transition Logic:
- transition.go's tJS function is updated to detect these comment tokens (<, -, #) and transition into the new states or the existing stateJSLineCmt for hashbang comments.
- transition.go's tLineCmt function is updated to treat these new JavaScript comment states like regular JavaScript line comments, terminating them at line endings.
Modified Escaping Logic: escape.go's (*escaper).escapeText function, which orchestrates the escaping process, is updated to correctly calculate offsets when these new comment types are encountered, ensuring that content around them is preserved or handled appropriately.

The functions (*escaper).escapeText, tJS, and tLineCmt are central to parsing and sanitizing template content, especially within script tags. The modifications directly show how the vulnerable parsing behavior was fixed. Therefore, these functions would be active and appear in a runtime profile when processing input that could trigger the vulnerability (i.e., input containing these special comment sequences in script contexts).

Vulnerable functions

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WAF Rule

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Reasoning

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