PT-2025-49294 · Nextcloud+1 · Nextcloud Mail+1

Published 2025-12-05 · Updated 2026-02-09 · CVE-2025-66514

Positive Technologies (AI Summary)

CVSS v3.1

5.4

Medium

Base vector

AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions Nextcloud Mail versions prior to 5.5.3

Description A stored HTML injection issue exists in the Mail app's message list, potentially allowing an authenticated user to inject HTML into email subjects. The Nextcloud Server’s content security policy blocks Javascript, mitigating some of the risk.

Recommendations Update Nextcloud Mail to version 5.5.3 or later.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

BDU:2026-03581

CVE-2025-66514

GHSA-V394-8GPC-6FV5

Affected Products

Nextcloud Mail

Red Os

References · 14

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66514.json · Exploit
• https://github.com/nextcloud/mail/commit/c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09 · Patch
• https://github.com/nextcloud/mail/pull/11740 · Patch
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-v394-8gpc-6fv5 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2025-66514 · Vendor Advisory
• https://hackerone.com/reports/3357036 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-03581 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2025-66514 · Security Note
• https://redos.red-soft.ru/support/secure/uyazvimosti/support/secure/uyazvimosti-red-os-8-0/uyazvimost-nextcloud-app-mail-cve-2025-66514-8.0 · Note
• https://redos.red-soft.ru/support/secure/uyazvimosti/uyazvimost-nextcloud-app-mail-cve-2025-66514-7.3/?sphrase_id=1456292 · Note
• https://t.me/cveNotify/145259 · Telegram Post
• https://t.me/CVEtracker/38944 · Telegram Post
• https://twitter.com/CVEnew/status/1997000965610775027 · Twitter Post
• https://redos.red-soft.ru/support/secure/uyazvimosti/support/secure/uyazvimosti/uyazvimost-nextcloud-app-mail-cve-2025-66514-7.3 · Note