Read the docs
TI-2026-29529 Aliases CVE-2026-40873

mailcow: dockerized vulnerable to stored XSS in Quarantine attachment filenames

Priority HIGH 74CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
Present
Impact type
Cross-site scripting
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0042 36th percentileScored 2026-11-07
Fix Fixed mailcow-dockerized (mailcow): 2026-03b

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mailcowmailcow-dockerizedbefore 2026-03b2026-03bPatch availableCNA
  • mailcow-dockerized Vendormailcow Affected before 2026-03b Fixed in 2026-03b Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:mailcow:mailcow\:*:*:*:*:*:*:*:*——mailcow
  • cpe:2.3:a:mailcow:mailcow\:*:*:*:*:*:*:*:* Versions — — ·mailcow

Remediation

  • Fix · CNA mailcow-dockerized (mailcow) Fixed in 2026-03b

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-40873

References

Other 1

  • TI-2026-29528 mailcow: dockerized vulnerable to stored XSS in autodiscover logs email address field CVSS 4.0CRITICAL 9.3
  • TI-2022-13182 OS Command Injection in mailcow CVSS 3.1HIGH 8.8
  • TI-2022-18634 mailcow-dockerized critical information misrepresentation can lead to phishing attacks through Swagger UI CVSS 3.1HIGH 8.2
  • TI-2026-06557 mailcow-dockerized 2026-03b - Stored XSS in Queue Manager via unescaped CVSS 4.0HIGH 7.4
  • TI-2026-29527 mailcow: dockerized vulnerable to Second Order SQL Injection in quarantine category via API CVSS 3.1HIGH 7.2
  • TI-2026-29531 mailcow: dockerized vulnerable to stored XSS in user login history real_rip CVSS 4.0HIGH 7.0
See all 22 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences