{"id":"CVE-2026-125757","kind":"vulnerability","aliases":["CVE-2026-125757"],"related":[],"title":"mailcow: domain admins can run commands in shared rspamd container","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.","summary":"mailcow dockerized before 2026-11 lets a domain administrator store a malicious domain-wide footer that is rendered as a Jinja template by the rspamd filter. The attacker can run commands in the shared rspamd container, read or inject mail for every tenant, and disable spam filtering.","severity":"critical","cvss":9.4,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mailcow","email","poc-public","rspamd","package","self-hosted"],"not_affected_if":["mailcow-at-or-above-2026-11","single-tenant"],"how_to_check":"- Check the mailcow version in the installed mailcow-dockerized repository (unknown exact command in sources)\n- Confirm whether the installation is below `2026-11`\n- Review domain footer settings for untrusted domain administrators","fix":"- mailcow dockerized: move to `2026-11` or later (per the sources' 'before 2026-11' range)","status":"open","published_at":"2026-11-10T16:17:23+00:00","first_seen_at":"2026-11-10T16:22:35+00:00","triaged_at":"2026-11-10T16:23:15+00:00","updated_at":"2026-11-10T16:39:55+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-10T16:23:15Z","model":"claude-haiku-5-5","output":{"fix":"- mailcow dockerized: move to `2026-11` or later (per the sources' 'before 2026-11' range)","reach":"network","title":"mailcow: domain admins can run commands in shared rspamd container","impact":"high","summary":"mailcow dockerized before 2026-11 lets a domain administrator store a malicious domain-wide footer that is rendered as a Jinja template by the rspamd filter. The attacker can run commands in the shared rspamd container, read or inject mail for every tenant, and disable spam filtering.","audience":"businesses","category":"package","nicknames":[],"who_cares":["mailcow","self-hosted","email","rspamd"],"confidence":0.7,"fix_status":"available","needs_auth":"yes","worst_case":"Code runs in shared filter container; all tenant mail readable.","analyst_note":"Confirm exact fixed version and whether a domain-admin footer setting is the only trigger, using the Vendor advisory and Patch links on github.com.","how_to_check":"- Check the mailcow version in the installed mailcow-dockerized repository (unknown exact command in sources)\n- Confirm whether the installation is below `2026-11`\n- Review domain footer settings for untrusted domain administrators","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["single-tenant","mailcow-at-or-above-2026-11"],"who_is_affected":"Hosts running mailcow dockerized before 2026-11 with multiple tenant domains, where domain administrators are not fully trusted. The flaw sits in the shared rspamd container, so one tenant's footer can reach every tenant's mail. Single-tenant installs with only trusted administrators carry less risk.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000775,"input_tokens":4650,"output_tokens":619,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-11':31B,79C '-125757':13A,16A '-2026':12A,15A '2026':30B,78C 'admin':3A 'administr':35B,91C 'allow':89C 'attack':55B,108C 'command':6A,58B,94C 'contain':10A,63B,80C,99C 'cve':11A,14A 'default':117C 'disabl':72B,135C 'docker':28B,76C 'domain':2A,34B,40B,90C,105C 'domain-wid':39B,104C 'email':18B 'emb':110C 'everi':69B,132C 'execut':93C 'filter':53B,74B,136C 'footer':42B,107C,124C 'host':26B 'inject':66B,86C,129C 'jinja':48B,112C 'let':32B 'macro':113C 'mail':67B,130C 'mailcow':1A,17B,27B,75C 'malici':38B,103C 'moo':123C 'os.execute':116C 'packag':23B 'poc':20B 'poc-publ':19B 'prefilt':125C 'public':21B 'read':64B,127C 'render':45B,119C 'rspamd':9A,22B,52B,62B,98C,122C 'run':5A,57B 'self':25B 'self-host':24B 'server':83C 'server-sid':82C 'share':8A,61B,97C 'side':84C 'spam':73B 'store':36B,101C 'templat':49B,85C 'tenant':70B,133C 'valu':118C 'vulner':87C 'wide':41B,106C","nicknames":[],"mitigations":[],"who_affected":"Hosts running mailcow dockerized before 2026-11 with multiple tenant domains, where domain administrators are not fully trusted. The flaw sits in the shared rspamd container, so one tenant's footer can reach every tenant's mail. Single-tenant installs with only trusted administrators carry less risk.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["critical","email","mailcow","package","pocpublic","rspamd","selfhosted"],"campaign_type":null,"search_a":"'-125757':13A,16A '-2026':12A,15A 'admin':3A 'command':6A 'contain':10A 'cve':11A,14A 'domain':2A 'mailcow':1A 'rspamd':9A 'run':5A 'share':8A","search_b":"'-11':31B '2026':30B 'administr':35B 'attack':55B 'command':58B 'contain':63B 'disabl':72B 'docker':28B 'domain':34B,40B 'domain-wid':39B 'email':18B 'everi':69B 'filter':53B,74B 'footer':42B 'host':26B 'inject':66B 'jinja':48B 'let':32B 'mail':67B 'mailcow':17B,27B 'malici':38B 'packag':23B 'poc':20B 'poc-publ':19B 'public':21B 'read':64B 'render':45B 'rspamd':22B,52B,62B 'run':57B 'self':25B 'self-host':24B 'share':61B 'spam':73B 'store':36B 'templat':49B 'tenant':70B 'wide':41B","search_c":"'-11':79C '2026':78C 'administr':91C 'allow':89C 'attack':108C 'command':94C 'contain':80C,99C 'default':117C 'disabl':135C 'docker':76C 'domain':90C,105C 'domain-wid':104C 'emb':110C 'everi':132C 'execut':93C 'filter':136C 'footer':107C,124C 'inject':86C,129C 'jinja':112C 'macro':113C 'mail':130C 'mailcow':75C 'malici':103C 'moo':123C 'os.execute':116C 'prefilt':125C 'read':127C 'render':119C 'rspamd':98C,122C 'server':83C 'server-sid':82C 'share':97C 'side':84C 'store':101C 'templat':85C 'tenant':133C 'valu':118C 'vulner':87C 'wide':106C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T11:41:44+00:00","kev":null,"cvss_vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":1,"sources":[{"source":"nvd","external_id":"CVE-2026-125757","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-125757","severity":null,"published_at":"2026-11-10T16:17:23+00:00","modified_at":"2026-11-10T16:17:23+00:00","first_seen_at":"2026-11-10T16:22:35+00:00","fetched_at":"2026-11-10T16:22:35+00:00","note":null},{"source":"github-poc","external_id":"Faceless0x7/CVE-2026-125757","url":"https://github.com/Faceless0x7/CVE-2026-125757","severity":null,"published_at":"2026-11-10T16:38:30+00:00","modified_at":null,"first_seen_at":"2026-11-10T16:39:55+00:00","fetched_at":"2026-11-10T16:39:55+00:00","note":null}],"documents":[{"id":116135,"url":"https://github.com/mailcow/mailcow-dockerized/commit/e986803980db8b29435a2ddba5d9760737a818e3","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":116136,"url":"https://github.com/mailcow/mailcow-dockerized/releases/tag/2026-11","title":"Release notes: github.com","kind":"release","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Release notes: github.com"},{"id":116137,"url":"https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jgr3-fv33-x43c","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-11-10T11:41:44+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":116138,"url":"https://www.vulncheck.com/advisories/mailcow-dockerized-before-2026-11-template-injection-rce-via-domain-wide-footer","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"},{"id":116297,"url":"https://github.com/Faceless0x7/CVE-2026-125757","title":"Faceless0x7/CVE-2026-125757","kind":"poc","source":"github","publisher":null,"text":"CVE-2026-125757 Exploit — mailcow domain-wide footer SSTI via rspamd's jinja/lupa engine, enabling cross-tenant RCE in the shared rspamd container.\n\nstars 0","published_at":"2026-11-10T16:38:30+00:00","relation":"poc","confidence":null,"note":"0 stars"}],"disclosures":[],"exploit_sources":[{"type":"poc","url":"https://github.com/Faceless0x7/CVE-2026-125757"}],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}