CVE-2026-59729

Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for CVE-2026-54298)

Published: Jul 27, 2026Updated: Jul 28, 2026 Sources: CVE List NVDCWE-79

N/ACVSS

NVD MITRE

Description

Astro is a web framework for content-driven websites. Versions prior to 7.0.6 are vulnerable to XSS through unescaped spread attribute names in renderHTMLElement. The fix for CVE-2026-54298 (GHSA-jrpj-wcv7-9fh9) added an INVALID_ATTR_NAME_CHAR guard to addAttribute() so that spread-prop attribute names containing "' >/= or whitespace are dropped. A second attribute-rendering path, renderHTMLElement() in packages/astro/src/runtime/server/render/dom.ts, has its own inline attribute loop that does not go through addAttribute() and was not updated. It interpolates the attribute name unescaped and only escapes the value, so untrusted prop keys spread onto a native-HTMLElement-subclass component can still break out of the attribute context. This issue has been fixed in version 7.0.6.

No summary for this CVE yet.

Weaknesses

CWE-79

Affected Products

withastro

oss-projectaka @astrojs/cloudflare, astro

astroLibrary

OSS Libraries / web-framework

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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References

https://github.com/withastro/astro/security/advisories/GHSA-f48w-9m4c-m7f5

github.com

https://github.com/withastro/astro/pull/17251

github.com

https://github.com/withastro/astro/commit/5240e26c9dd91f9bc7140dcfacdb48d5a132830d

github.com

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