mailcow mailcow-dockerized prior 2026-03b Attachment 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 was found in mailcow mailcow-dockerized. It has been classified as problematic. This impacts an unknown function of the component Attachment Handler. Performing a manipulation results in cross site scripting. This vulnerability is reported as CVE-2026-40873. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in mailcow mailcow-dockerized. This affects an unknown code block of the component Attachment Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the Quarantine details modal injects attachment filenames into HTML without escaping, allowing arbitrary HTML/JS execution. An attacker can deliver an email with a crafted attachment name so that when an admin views the quarantine item, JavaScript executes in their browser, taking over their account. Version 2026-03b fixes the vulnerability.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-40873 since 04/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 2026-03b eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

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-79 / CWE-94 / CWE-74
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: mailcow-dockerized 2026-03b

Timelineinfo

04/15/2026 CVE reserved
04/21/2026 +6 days Advisory disclosed
04/21/2026 +0 days VulDB entry created
04/21/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-2xjc-rg88-jvpp
Status: Confirmed

CVE: CVE-2026-40873 (🔒)
GCVE (CVE): GCVE-0-2026-40873
GCVE (VulDB): GCVE-100-358587
scip Labs: https://www.scip.ch/en/?labs.20171019

Entryinfo

Created: 04/21/2026 22:35
Changes: 04/21/2026 22:35 (68)
Complete: 🔍
Cache ID: 216::103

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