#VU102548 Cross-site scripting in Backdrop CMS

Vulnerability identifier: #VU102548

Vulnerability risk: Low

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: N/A

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Backdrop CMS
Web applications / CMS

Vendor: Backdrop CMS

Description

The disclosed vulnerability allows a remote user to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data when handling long content with the CKEditor 5 rich text editor module. A remote user can inject specially crafted content, trick the website administrator into opening the specially crafted content with the CKEditor 5 module and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Backdrop CMS: 1.20.0 - 1.29.2

---

External links
https://backdropcms.org/security/backdrop-sa-core-2025-001

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.