CVE-2026-125757
mailcow: dockerized before 2026-11 Template Injection RCE via Domain-Wide Footer
mailcow: dockerized before 2026-11 contains a server-side template injection vulnerability that allows domain administrators to execute commands in the shared rspamd container by storing a malicious domain-wide footer. Attackers can embed a Jinja macro with an os.execute default value, rendered by the rspamd MOO_FOOTER prefilter, to read or inject mail for every tenant and disable filtering.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| mailcow: dockerized mailcow mailcow/mailcow-dockerized
github |
≥ 0; < 2026-11 (affected, custom)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 9.4 critical |
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H | CNA: VulnCheck |
| 3.1 / 9.1 critical |
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H | CNA: VulnCheck |
Exploit evidence
- https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c
exploit · ADP: CISA-ADP
References
- https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43cCNA: VulnCheck · vendor-advisory
- https://github.com/mailcow/mailcow-dockerized/commit/e986803980db8b29435a2ddba5d9760737a818e3CNA: VulnCheck · patch
- https://github.com/mailcow/mailcow-dockerized/releases/tag/2026-11CNA: VulnCheck · release-notes
- https://github.com/mailcow/mailcow-dockerized/blob/55982ac74bfd35581cc44b122ab5fc659e3ae90a/data/conf/rspamd/lua/rspamd.local.lua#L847-L850CNA: VulnCheck · technical-description
- https://www.vulncheck.com/advisories/mailcow-dockerized-before-2026-11-template-injection-rce-via-domain-wide-footerCNA: VulnCheck · third-party-advisory
- https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43cADP: CISA-ADP · exploit
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