CVE-2026-40873 | mailcow mailcow-dockerized prior 2026-03b Attachment cross site scripting (GHSA-2xjc-rg88-jvpp)

VDB-358587 · CVE-2026-40873 · GHSA-2XJC-RG88-JVPP MAILCOW MAILCOW-DOCKERIZED PRIOR 2026-03B ATTACHMENT CROSS SITE SCRIPTING HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.1 $0-$5k 2.80+ 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. Productinfo Type Virtualization Software Vendor mailcow Name mailcow-dockerized Website Product: https://github.com/mailcow/mailcow-dockerized/ 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 Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock 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 Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock 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: 99:E03:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸