{"id":"CVE-2026-125757","published":"2026-11-10T16:17:23.107","lastModified":"2026-11-10T17:17:31.177","description":"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.","cvssScore":9.1,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H","cwes":["CWE-1336"],"vendors":[],"products":[],"references":[{"url":"https://github.com/mailcow/mailcow-dockerized/blob/55982ac74bfd35581cc44b122ab5fc659e3ae90a/data/conf/rspamd/lua/rspamd.local.lua#L847-L850","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/commit/e986803980db8b29435a2ddba5d9760737a818e3","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/releases/tag/2026-11","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c","tags":[]},{"url":"https://www.vulncheck.com/advisories/mailcow-dockerized-before-2026-11-template-injection-rce-via-domain-wide-footer","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c","tags":[]}],"exploitRefs":[{"url":"https://github.com/mailcow/mailcow-dockerized/blob/55982ac74bfd35581cc44b122ab5fc659e3ae90a/data/conf/rspamd/lua/rspamd.local.lua#L847-L850","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/commit/e986803980db8b29435a2ddba5d9760737a818e3","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/releases/tag/2026-11","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c","tags":[]},{"url":"https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c","tags":[]}],"hasPoc":true,"ai":{"summary":"A server-side template injection (CWE-1336) in mailcow before 2026-11 allows domain administrators to inject malicious Jinja macros into domain-wide footers, which are rendered by the rspamd MOO_FOOTER prefilter, enabling arbitrary command execution in the shared rspamd container. This bypasses tenant isolation and allows attackers to read or inject mail for all tenants and disable spam filtering.","exploitability":"Exploitation requires domain administrator privileges and knowledge of the vulnerable rspamd prefilter configuration; no external authentication bypass is needed beyond valid admin credentials.","blast_radius":"Successful exploitation compromises all mailboxes and filtering across all tenants sharing the same rspamd instance, enabling full data exfiltration, mail injection, and persistent filter disabling.","remediation":"Upgrade to mailcow dockerized 2026-11 or later, which patches the template injection in the domain footer rendering logic.","detection":"Defenders should monitor rspamd logs for unexpected os.execute() calls or suspicious macro invocations in MOO_FOOTER context; additionally, inspect mailcow admin activity logs for creation or modification of domain-wide footers containing Jinja syntax with dangerous functions like {{ ''.__class__.__mro__[1].__subclasses__() }} or os.execute().","tags":["rce","ssti","tenant-isolation-bypass","mailcow","rspamd","admin-privilege-abuse"],"model":"garnet-coder","analyzedAt":"2026-11-11T09:58:10.164Z"}}