XSS in Light Messages Project

CVE-2021-24535

The Light Messages WordPress plugin through 1.0 is lacking CSRF check when updating it's settings, and is not sanitising its Message Content in them (even with the unfiltered_html disallowed). As a result, an attacker could make a logged in admin update the settings to arbitrary values, and set a Cross-Site Scripting payload in the Message Content. Depending on the options set, the XSS payload can be triggered either in the backend only (in the plugin's settings), or both frontend and backend.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.004 (34.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-24535?
CVE-2021-24535 is a medium-severity vulnerability in Light Messages Project, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-08-16.
How severe is CVE-2021-24535?
Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2021-24535 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.