Vulnerability Report

CVE-2025-66514

Title: Nextcloud Mail App Stored HTML Injection

XSS

Proof Of Concept

No public PoC currently indexed for CVE-2025-66514.

CWE Category CWE-79
Published Date Dec 05, 2025
Modified Date Dec 09, 2025
Exploit Status Not Found
Score 3.5 CVSS v3.1
Exploit Probability (EPSS)
0.02%

Vulnerability Summary

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

Impacted Vendors

P
pear 1
B
basercms 1
N
nextcloud 1

Reference Links

https://github.com/nextcloud/mail/commit/c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09 https://github.com/nextcloud/mail/pull/11740 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-v394-8gpc-6fv5 https://hackerone.com/reports/3357036
CVSS v3.1
Source Entity [email protected]
Severity LOW
3.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.4
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2025-66514 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data or affected products updated.

MODIFIED

Vulnerability data updated via NVD.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction REQUIRED
CVSS Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Affected Stack

No specific products linked.