Hugo's default fenced-code-block renderer writes attribute values taken from the code-fence info string into the rendered HTML without escaping them. New in markup/internal/attributes/attributes.go converts every attribute value from a byte slice to a string as it is stored, deliberately dropping the escaping that used to happen there, and RenderAttributes in the same file escapes only values that are still byte slices, so its escaping branch is never reached and every value is written verbatim. The function's documentation states that it performs HTML escaping of string attributes, which it does not. A quote inside an attribute value in the info string therefore terminates the attribute and allows a further attribute, including an event handler, to be placed on the wrapper element, and the script runs for every visitor who loads the page. This path is reached under the default configuration, with code fences enabled and without goldmark's unsafe setting or any custom render hook. Attribute names beginning with on are filtered when the attributes are parsed, so injection is achieved through the value rather than the name.
Metrics
Affected Vendors & Products
References
History
Mon, 24 Aug 2026 11:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Gohugo
Gohugo hugo |
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| CPEs | cpe:2.3:a:gohugo:hugo:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Gohugo
Gohugo hugo |
Mon, 24 Aug 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Hugo's default fenced-code-block renderer writes attribute values taken from the code-fence info string into the rendered HTML without escaping them. New in markup/internal/attributes/attributes.go converts every attribute value from a byte slice to a string as it is stored, deliberately dropping the escaping that used to happen there, and RenderAttributes in the same file escapes only values that are still byte slices, so its escaping branch is never reached and every value is written verbatim. The function's documentation states that it performs HTML escaping of string attributes, which it does not. A quote inside an attribute value in the info string therefore terminates the attribute and allows a further attribute, including an event handler, to be placed on the wrapper element, and the script runs for every visitor who loads the page. This path is reached under the default configuration, with code fences enabled and without goldmark's unsafe setting or any custom render hook. Attribute names beginning with on are filtered when the attributes are parsed, so injection is achieved through the value rather than the name. | |
| Title | Hugo 0.93.0 through 0.165.0 Stored Cross-Site Scripting via Unescaped Code-Fence Attribute Values | |
| Weaknesses | CWE-79 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-08-24T11:13:21.240Z
Reserved: 2026-06-02T13:53:48.666Z
Link: CVE-2026-10618
No data.
Status : Received
Published: 2026-08-24T11:16:38.403
Modified: 2026-08-24T11:16:38.403
Link: CVE-2026-10618
No data.
OpenCVE Enrichment
Updated: 2026-08-24T11:30:03Z