vulnerability / NVI-00005326 / Revision 3
Winter CMS Stored XSS through Backend ColorPicker FormWidget
OSV carries this publisher advisory for winter/wn-backend-module. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
0.309%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.23725. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
winter/wn-backend-module
source listedECOSYSTEM: introduced 0; fixed 1.2.4
### Impact Users with access to backend forms that include a ColorPicker FormWidget can provide a value that would then be rendered unescaped in the backend form, potentially allowing for a stored XSS attack. By default, only the Brand Settings (`backend.manage_branding`) and Mail Brand Settings (`system.manage_mail_templates`) forms include the `colorpicker` formwidget, however it is also common for theme's to include it on their Theme Customization (`cms.manage_theme_options`) form. Although this was a security issue, it's important to note that its severity is relatively low. To exploit the vulnerability, an attacker would already need to have trusted access to the Winter CMS backend and they would then need to convince a user with higher privileges than them to visit an affected Form in the backend. These two factors limit the potential harm of this vulnerability. That being said, all users are advised to update to the latest version (1.2.4) to ensure their systems remain secure. ### Patches This issue has been patched in v1.2.4. ### Workarounds Apply https://github.com/wintercms/winter/commit/517f65dfae679
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 1.2.4 for winter/wn-backend-module. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-43w4-4j3c-jx29 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2023-52084 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.