XSS in Nextcloud Mail
CVE-2025-66514
Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity platform. Prior to 5.5.3, a stored HTML injection in the Mail app's message list allowed an authenticated user to inject HTML into the email subjects. Javascript was…
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.002 (10.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N.
Affected products
- Nextcloud Mail
- Nextcloud Security-advisories — versions >= 5.2.0-beta.1, < 5.5.3
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Permissions Required, x_refsource_MISC, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-66514?
- CVE-2025-66514 is a low-severity vulnerability in Nextcloud Mail, classified under Cross-site Scripting. CVSS score: 3.5/10. Published 2025-12-05.
- How severe is CVE-2025-66514?
- Low severity. CVSS v3 base score is 3.5 out of 10.