Vulnerability record · CVE-2026-40873 · published 21 April 2026

CVE-2026-40873: Cross-site scripting vulnerability

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.

8.9 CVSS 4.0 High EPSS 0.55% · top 56.2% CWE-79 · Cross-site scriptingCWE-80 · CWE-80 Deferred

8.9CVSS 4.0 base score

0.55%EPSS exploitation probability, 30 days

NoNot in CISA KEV

0Affected product versions listed by NVD

2References

17 Jun 2026Last modified by NVD

Description

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

Link	Tags
https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-2xjc-rg88-jvpp
https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-2xjc-rg88-jvpp

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-40873), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.