Medium 5.4Published Dec 5, 2025

CVE-2025-66514Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity platform.

Updated under an hour ago (2026-10-19 07:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for nextcloud mail

Exploited in the last 30 days

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 correctly blocked by the content security policy of the Nextcloud Server code.

CVSS: 5.4 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nextcloud mail nextcloud:mail	before 5.5.3	NVD

References

https://github.com/nextcloud/mail/commit/c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09patch
https://github.com/nextcloud/mail/pull/11740issue-tracking, patch
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-v394-8gpc-6fv5patch, vendor-advisory
https://hackerone.com/reports/3357036permissions-required, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.