Backdrop CMS before 1.27.3 and 1.28.x before 1.28.2 does not sufficiently sanitize field labels before they are displayed in certain places. This vulnerability is mitigated by the fact that an attacker must have a role with the "administer fields" permission.

DISPUTED A stored Cross-site scripting (XSS) issue in Text Editors and Formats in Backdrop CMS before 1.24.2 allows remote attackers to inject arbitrary web script or HTML via the name parameter. When a user is editing any content type (e.g., page, post, or card) as an admin, the stored XSS payload is executed upon selecting a malicious text formatting option. NOTE: the vendor disputes the security relevance of this finding because "any administrator that can configure a text format could easily allow Full HTML anywhere."

Backdrop CMS version 1.23.0 was discovered to contain a stored cross-site scripting (XSS) vulnerability via the 'Card' content.

Backdrop CMS version 1.23.0 was discovered to contain a stored cross-site scripting (XSS) vulnerability via 'Comment.' .

A Prototype Pollution vulnerability was found in jquery. Untrusted JSON passed to the extend function could lead to modifying objects up the prototype chain, including the global Object. A crafted JSON object passed to a vulnerable method could lead to denial of service or data injection, with various consequences.