{"id":"CVE-2026-120331","kind":"vulnerability","aliases":["CVE-2026-120331"],"related":[],"title":"Mail module fetches external URLs without host checks, enabling internal requests","description":"Content of external URL mails, their stylesheets and images to embed is fetched by the server without validating the target host. Backend users with access to the mail module can make the server send requests to hosts in the internal network.","summary":"The server fetches the contents, stylesheets and images of external URL mails without validating the target host. A backend user with access to the mail module can make the server send requests to hosts on the internal network (server-side request forgery).","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mail-module","other","self-hosted"],"not_affected_if":["backend-access-restricted","mail-module-unused"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-03T10:17:17+00:00","first_seen_at":"2026-11-03T10:20:16+00:00","triaged_at":"2026-11-03T10:20:39+00:00","updated_at":"2026-11-03T10:20:39+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-11-03T10:20:39Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Mail module fetches external URLs without host checks, enabling internal requests","impact":"medium","summary":"The server fetches the contents, stylesheets and images of external URL mails without validating the target host. A backend user with access to the mail module can make the server send requests to hosts on the internal network (server-side request forgery).","audience":"businesses","category":"other","nicknames":[],"who_cares":["mail-module","self-hosted"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"server reaches internal hosts and returns their responses to attacker","analyst_note":"Identify the affected product and versions from https://nvd.nist.gov/vuln/detail/CVE-2026-120331 and find the vendor's fixed release.","how_to_check":"unknown","plain_action":"","needs_analyst":true,"not_affected_if":["mail-module-unused","backend-access-restricted"],"who_is_affected":"Affects products whose mail module fetches external URLs for mail content, and only for backend users who already have access to that module. Systems where the mail module is not used, or where backend access is restricted to trusted staff, carry lower risk. The sources do not name the affected product or versions.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000638,"input_tokens":4082,"output_tokens":460,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-120331':14A,17A '-2026':13A,16A 'access':46B,92C 'backend':43B,89C 'check':8A 'content':29B,68C 'cve':12A,15A 'emb':78C 'enabl':9A 'extern':4A,34B,70C 'fetch':3A,27B,80C 'forgeri':67B 'host':7A,24B,41B,58B,88C,104C 'imag':32B,76C 'intern':10A,61B,107C 'mail':1A,19B,36B,49B,72C,95C 'mail-modul':18B 'make':52B,98C 'modul':2A,20B,50B,96C 'network':62B,108C 'request':11A,56B,66B,102C 'self':23B 'self-host':22B 'send':55B,101C 'server':26B,54B,64B,83C,100C 'server-sid':63B 'side':65B 'stylesheet':30B,74C 'target':40B,87C 'url':5A,35B,71C 'user':44B,90C 'valid':38B,85C 'without':6A,37B,84C","nicknames":[],"mitigations":[],"who_affected":"Affects products whose mail module fetches external URLs for mail content, and only for backend users who already have access to that module. Systems where the mail module is not used, or where backend access is restricted to trusted staff, carry lower risk. The sources do not name the affected product or versions.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["mailmodule","medium","other","selfhosted"],"first_public_at":"2026-11-03T10:17:17+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/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":"f4fb688c-4412-4426-b4b8-421ecf27b14a","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120331","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120331","severity":null,"published_at":"2026-11-03T10:17:17+00:00","modified_at":"2026-11-03T10:17:17+00:00","first_seen_at":"2026-11-03T10:20:16+00:00","fetched_at":"2026-11-03T10:20:16+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"}