{"id":"CVE-2026-113599","kind":"vulnerability","aliases":["CVE-2026-113599"],"related":[],"title":"Modoboa: authenticated users can write auto-replies to other mailboxes","description":"Modoboa before 2.8.0 contains an insecure direct object reference vulnerability that allows authenticated users to create auto-reply messages for arbitrary mailboxes by supplying another user's mbox value. Attackers can POST to /api/v2/armessages/ to inject attacker-controlled auto-reply subject and content into victims' settings or break their auto-reply management via MultipleObjectsReturned errors.","summary":"Modoboa before 2.8.0 has an insecure direct object reference in its auto-reply API: an authenticated user can post to /api/v2/armessages/ with another user's mbox value. An attacker can inject their own auto-reply subject and content into a victim's mailbox settings, or break the victim's auto-reply management with MultipleObjectsReturned errors.","severity":"medium","cvss":5.4,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mail-server","modoboa","package","self-hosted"],"not_affected_if":["modoboa-2.8.0-or-later","no-untrusted-accounts"],"how_to_check":"- Check the installed Modoboa version (for example `pip show modoboa` or the version in the deployment's requirements) and see whether it is below `2.8.0`.\n- Confirm the auto-reply API is reachable: `POST /api/v2/armessages/` on the Modoboa host.","fix":"- Upgrade Modoboa to `2.8.0` or later.\n- Until upgraded, restrict who can authenticate to the Modoboa web interface and API.","status":"open","published_at":"2026-10-20T16:17:09+00:00","first_seen_at":"2026-10-23T21:57:20+00:00","triaged_at":"2026-10-25T04:16:32+00:00","updated_at":"2026-10-25T04:16:32+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T04:16:32Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Modoboa to `2.8.0` or later.\n- Until upgraded, restrict who can authenticate to the Modoboa web interface and API.","reach":"internet","title":"Modoboa: authenticated users can write auto-replies to other mailboxes","impact":"medium","summary":"Modoboa before 2.8.0 has an insecure direct object reference in its auto-reply API: an authenticated user can post to /api/v2/armessages/ with another user's mbox value. An attacker can inject their own auto-reply subject and content into a victim's mailbox settings, or break the victim's auto-reply management with MultipleObjectsReturned errors.","category":"package","nicknames":[],"who_cares":["modoboa","self-hosted","mail-server"],"confidence":0.6,"needs_auth":"yes","worst_case":"Attacker writes auto-reply text into other users' mailboxes and disrupts their settings.","analyst_note":"","how_to_check":"- Check the installed Modoboa version (for example `pip show modoboa` or the version in the deployment's requirements) and see whether it is below `2.8.0`.\n- Confirm the auto-reply API is reachable: `POST /api/v2/armessages/` on the Modoboa host.","needs_analyst":false,"not_affected_if":["modoboa-2.8.0-or-later","no-untrusted-accounts"],"who_is_affected":"Modoboa installations before 2.8.0 where users hold accounts that can reach the auto-reply API. Exposure comes from any authenticated mail user, so the risk is greatest on multi-tenant or self-service mail servers. Single-admin installs with no other users have little exposure.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000642,"input_tokens":3356,"output_tokens":613,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-113599':14A,17A '-2026':13A,16A '/api/v2/armessages':47B,118C '2.8.0':28B,86C 'allow':95C 'anoth':49B,109C 'api':40B 'arbitrari':105C 'attack':55B,114C,122C 'attacker-control':121C 'authent':2A,42B,96C 'auto':7A,38B,61B,78B,101C,125C,137C 'auto-repli':6A,37B,60B,77B,100C,124C,136C 'break':73B,134C 'contain':87C 'content':65B,129C 'control':123C 'creat':99C 'cve':12A,15A 'direct':32B,90C 'error':83B,142C 'host':25B 'inject':57B,120C 'insecur':31B,89C 'mail':19B 'mail-serv':18B 'mailbox':11A,70B,106C 'manag':80B,139C 'mbox':52B,112C 'messag':103C 'modoboa':1A,21B,26B,84C 'multipleobjectsreturn':82B,141C 'object':33B,91C 'packag':22B 'post':45B,116C 'refer':34B,92C 'repli':8A,39B,62B,79B,102C,126C,138C 'self':24B 'self-host':23B 'server':20B 'set':71B,132C 'subject':63B,127C 'suppli':108C 'user':3A,43B,50B,97C,110C 'valu':53B,113C 'via':140C 'victim':68B,75B,131C 'vulner':93C 'write':5A","nicknames":[],"mitigations":[],"who_affected":"Modoboa installations before 2.8.0 where users hold accounts that can reach the auto-reply API. Exposure comes from any authenticated mail user, so the risk is greatest on multi-tenant or self-service mail servers. Single-admin installs with no other users have little exposure.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T16:17:09+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/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":0,"sources":[{"source":"nvd","external_id":"CVE-2026-113599","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-113599","severity":null,"published_at":"2026-10-20T16:17:09+00:00","modified_at":"2026-10-20T20:11:29+00:00","first_seen_at":"2026-10-23T21:57:20+00:00","fetched_at":"2026-10-23T22:28:58+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}