Nextcloud Mail up to 5.5.2 Message cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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4.1$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in Nextcloud Mail up to 5.5.2. This vulnerability affects unknown code of the component Message Handler. Performing a manipulation results in cross site scripting. This vulnerability is reported as CVE-2025-66514. The attack is possible to be carried out remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Nextcloud Mail up to 5.5.2. This affects some unknown processing of the component Message Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-80. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages. This is going to have an impact on integrity. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2025-66514 since 12/03/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 5.5.3 eliminates this vulnerability. Applying the patch c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.1
VulDB Meta Temp Score: 4.1

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔒

CNA Base Score: 3.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-80 / CWE-74 / CWE-707
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mail 5.5.3
Patch: c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09

Timelineinfo

12/03/2025 CVE reserved
12/06/2025 +3 days Advisory disclosed
12/06/2025 +0 days VulDB entry created
12/09/2025 +3 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-v394-8gpc-6fv5
Status: Confirmed

CVE: CVE-2025-66514 (🔒)
GCVE (CVE): GCVE-0-2025-66514
GCVE (VulDB): GCVE-100-334557

Entryinfo

Created: 12/06/2025 05:02
Updated: 12/09/2025 21:36
Changes: 12/06/2025 05:02 (68), 12/09/2025 21:36 (11)
Complete: 🔍
Cache ID: 216::103

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