PT-2026-34057 · Unknown · Mailcow-Dockerized

CVE-2026-40878 · Published 2026-04-21 · Updated 2026-04-21

Positive Technologies (AI Summary)

CVSS v4.0

2.1

Low

Base vector

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

Name of the Vulnerable Software and Affected Versions mailcow: dockerized versions prior to 2026-03b

Description The web interface passes the raw $ SERVER['REQUEST URI'] to Twig as a global template variable, which is then rendered inside a JavaScript string literal in the setLang() helper of base.twig. The system relies on default HTML auto-escaping instead of the required js escaping strategy. Furthermore, the query string() Twig helper merges all current $ GET parameters into language-switching links on the login page, allowing attacker-supplied parameters to be reflected and preserved during navigation.

Recommendations Update to version 2026-03b.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-40878

GHSA-XV9R-J862-5HQF

Affected Products

Mailcow-Dockerized

References · 4

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40878.json · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-40878 · Security Note
• https://osv.dev/vulnerability/CVE-2026-40878 · Vendor Advisory
• https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-xv9r-j862-5hqf · Note