ApostropheCMS: Color field validation bypass allows stored XSS via HTML appended after rgb()/hsl() prefix

### Summary The color field accepts any string that *begins* with a valid `rgb()` / `hsl()` color, because `TinyColor.isValid` does not anchor its match at the end of the string. An authenticated user with edit rights can store arbitrary HTML after a valid color prefix. When the stored value is rendered , the payload executes, resulting in stored XSS. ### Details Server-side validation of the color field relies on TinyColor: ```js const { TinyColor } = require('@ctrl/tinycolor'); if (!new TinyColor(value).isValid) throw self.apos.error('invalid'); ``` TinyColor's `rgb`/`hsl` matchers are not anchored at the end of the string, while hex matchers are. Tested with @ctrl/tinycolor | Input | `isValid` | |---|---| | `rgb(1,2,3)<img src=x onerror=alert(1)>` | `true` | | `rgb(1,2,3)</textarea><script>alert(1)</script>` | `true` | | `hsl(0,100%,50%);--x:1}</style><script>alert(1)</script>` | `true` | | `#ff0000<img src=x onerror=alert(1)>` | `false` | The value is saved to MongoDB unchanged (not normalized to hex8). ### Relation to GHSA-97v6-998m-fp4g GHSA-97v6 addressed CSS custom property injection escaping a `<style>` context. The root cause (validation that accepts trailing content after a valid color) still exists in <= 4.32.2, so [FILL IN: either "the style-tag sink remains exploitable via `</style>`" OR "a separate HTML sink at X is exploitable"]. Fixing the validation (requiring the full string to be a color, or storing only TinyColor's normalized output) would close both. ### Impact Any user with edit permission can plant persistent JavaScript that runs in the browser of visitors and administrators viewing the affected page, enabling session hijacking and actions as an admin. ### Suggested fix Reject values unless the entire string is a valid color, e.g. normalize on save: ```js const c = new TinyColor(value); if (!c.isValid) throw self.apos.error('invalid'); value = c.toHex8String(); // store only normalized output ```

Source published

21 Oct 2026 17:05:44 UTC

Source modified

21 Oct 2026 17:15:08 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Publisher rating · MODERATE