Summary
Winter CMS stored XSS through privileged upload of SVG file
Workarounds
Apply https://github.com/wintercms/storm/commit/186d85d8fea2cae43afc807d39f68553c24e56be & https://github.com/wintercms/winter/commit/fa50b4c7489b67ea80072f8ac9fe5294fce1df1c manually if unable to upgrade to v1.2.3.
Impact
Users with the backend.manage_branding permission can upload SVGs as the application logo. Previously, SVG uploads were not sanitized, which could have allowed a stored XSS attack.
Although this was a security issue, it's important to note that its severity is low. To exploit the vulnerability, an attacker would already need to have developer or super user level permissions in Winter CMS. This means they would already have extensive access and control within the system. Additionally, to execute the XSS, the attacker would need to convince the victim to directly visit the URL of the maliciously uploaded SVG, and the application would have to be using local storage where uploaded files are served under the same domain as the application itself instead of a CDN. This is because all SVGs in Winter CMS are rendered through an img tag, which prevents any payloads from being executed directly.
These two factors significantly limit the potential harm of this vulnerability. That being said, all users are advised to update to the latest version (1.2.3) to ensure their systems remain secure.
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.
CVE-2023-37269 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 (1.2.3); 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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This issue has been patched in v1.2.3 through the inclusion of full support for SVG uploads and automatic sanitization of uploaded SVG files.
Frequently Asked Questions
- What is CVE-2023-37269? CVE-2023-37269 is a low-severity cross-site scripting (XSS) vulnerability in wintercms/winter (composer), affecting versions < 1.2.3. It is fixed in 1.2.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2023-37269? CVE-2023-37269 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 wintercms/winter are affected by CVE-2023-37269? wintercms/winter (composer) versions < 1.2.3 is affected.
- Is there a fix for CVE-2023-37269? Yes. CVE-2023-37269 is fixed in 1.2.3. Upgrade to this version or later.
- Is CVE-2023-37269 exploitable, and should I be worried? Whether CVE-2023-37269 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 CVE-2023-37269 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 CVE-2023-37269? Upgrade
wintercms/winterto 1.2.3 or later.