Summary
Winter: Stored XSS through Backend List widget image columns
Workarounds
Apply the commit above to modules/backend/widgets/Lists.php manually if you are unable to upgrade to v1.2.14.
References
- https://github.com/wintercms/winter/security/advisories/GHSA-43w4-4j3c-jx29
- https://github.com/wintercms/winter/commit/0941c9816181095fe35d58e78e6d0c4a49238967
Credit to Seungyeon Park (@sy460129) for reporting the issue.
For more information
If you have any questions or comments about this advisory:
- Email us at [email protected]
Impact
Backend\Widgets\Lists::evalImageTypeValue() interpolated the resolved image URL into a single-quoted src attribute without escaping it. Where a list column of type image rendered an attacker-influenced value, that value could break out of the attribute and inject arbitrary attributes, including event handlers, into the backend list, executing in the session of whichever backend user viewed it.
Winter core ships no image list column, so a default installation is unaffected. Exploitation requires a plugin that renders attacker-influenced values through one.
The supported image sources are plugins, themes, the Media Library, the uploads directory, and Attach\File models; an arbitrary external URL is not among them. ImageResizer::filterGetUrl() returns the value it was given when it cannot resolve an image, however, so an unsupported value reached the attribute verbatim rather than being rejected.
As with previous issues of this kind the severity is limited: an attacker must already be able to store the value, and a backend user must then open the affected list. Note that validating a stored URL was not necessarily sufficient, a payload can survive filter_var($url, FILTER_VALIDATE_URL), since / is valid both in a URL path and after a quoted HTML attribute value.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
GHSA-7MPF-4465-7FC2 has a CVSS score of 2.0 (Low). The vector is network-reachable, high privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.2.14); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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evalImageTypeValue() now escapes the image URL, along with the width and height taken from the column configuration, before interpolating them into the tag.
This security issue has been fixed as of v1.2.14 (commit 0941c9816181095fe35d58e78e6d0c4a49238967).
Frequently Asked Questions
- What is GHSA-7MPF-4465-7FC2? GHSA-7MPF-4465-7FC2 is a low-severity cross-site scripting (XSS) vulnerability in winter/wn-backend-module (composer), affecting versions >= 1.1.0, < 1.2.14. It is fixed in 1.2.14. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is GHSA-7MPF-4465-7FC2? GHSA-7MPF-4465-7FC2 has a CVSS score of 2.0 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of winter/wn-backend-module are affected by GHSA-7MPF-4465-7FC2? winter/wn-backend-module (composer) versions >= 1.1.0, < 1.2.14 is affected.
- Is there a fix for GHSA-7MPF-4465-7FC2? Yes. GHSA-7MPF-4465-7FC2 is fixed in 1.2.14. Upgrade to this version or later.
- Is GHSA-7MPF-4465-7FC2 exploitable, and should I be worried? Whether GHSA-7MPF-4465-7FC2 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-7MPF-4465-7FC2 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-7MPF-4465-7FC2? Upgrade
winter/wn-backend-moduleto 1.2.14 or later.