CVE-2026-40873

HIGH

mailcow: dockerized vulnerable to stored XSS in Quarantine attachment filenames

Title source: cna

Description

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.

References (1)

[X_Refsource_Confirm] https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-2xjc-rg88-jvpp

Scores

CVSS v4 8.9

EPSS 0.0010

EPSS Percentile 27.7%

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:N

CISA SSVC

Vulnrichment

Exploitation poc

Automatable no

Technical Impact total

Details

CWE

CWE-79 CWE-80

Status published

Products (1)

mailcow/mailcow-dockerized < 2026-03b

Published Apr 21, 2026

Tracked Since Apr 22, 2026