{"id":"CVE-2018-6789","kind":"vulnerability","aliases":["CVE-2018-6789"],"related":[],"title":"Exim Exim: Exim Buffer Overflow Vulnerability","description":"Exim contains a buffer overflow vulnerability in the base64d function part of the SMTP listener that may allow for remote code execution.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Exim's SMTP listener has a buffer overflow in its base64d function, which an unauthenticated remote sender can trigger. The flaw may allow remote code execution on the mail server.","severity":"critical","cvss":9.8,"epss":0.82137,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Exim Exim","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exim","exploited","mail-server","package","ransomware","self-hosted"],"not_affected_if":["managed-mail-service"],"how_to_check":"Run exim -bV to see the installed version and compare it with the fixed release in the vendor advisory.","fix":"Upgrade Exim to a release that includes the vendor fix; CISA directs federal users to apply the vendor update.","status":"open","published_at":"2018-02-08T23:29:01+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:35+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-23T21:39:35Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade Exim to a release that includes the vendor fix; CISA directs federal users to apply the vendor update.\nunknown","reach":"internet","impact":"high","summary":"Exim's SMTP listener has a buffer overflow in its base64d function, which an unauthenticated remote sender can trigger. The flaw may allow remote code execution on the mail server.","category":"package","who_cares":["exim","mail-server","self-hosted"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker runs code on the mail server over the network","analyst_note":"Confirm affected and fixed Exim versions and the exact trigger conditions from the Exim security advisory or NVD entry for CVE-2018-6789.","how_to_check":"Run exim -bV to see the installed version and compare it with the fixed release in the vendor advisory.\nunknown\nunknown","needs_analyst":true,"not_affected_if":["managed-mail-service"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000466,"input_tokens":2817,"output_tokens":369,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2018':8A,11A '-6789':9A,12A 'action':79C 'allow':47B,72C 'appli':80C 'base64d':35B,63C 'buffer':4A,31B,58C 'cisa':77C 'code':49B,75C 'contain':56C 'cve':7A,10A 'execut':50B,76C 'exim':1A,2A,3A,13A,14A,15B,25B,55C 'exploit':16B 'flaw':45B 'function':36B,64C 'host':24B 'instruct':84C 'listen':28B,69C 'mail':18B,53B 'mail-serv':17B 'may':46B,71C 'overflow':5A,32B,59C 'packag':20B 'part':65C 'per':82C 'ransomwar':21B 'remot':40B,48B,74C 'requir':78C 'self':23B 'self-host':22B 'sender':41B 'server':19B,54B 'smtp':27B,68C 'trigger':43B 'unauthent':39B 'updat':81C 'vendor':83C 'vulner':6A,60C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2018-02-08T23:29:01+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2018-6789","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-6789","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T17:39:59+00:00","note":null},{"source":"epss","external_id":"CVE-2018-6789","url":"https://api.first.org/data/v1/epss?cve=CVE-2018-6789","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2018-6789","url":"https://nvd.nist.gov/vuln/detail/CVE-2018-6789","severity":null,"published_at":"2018-02-08T23:29:01+00:00","modified_at":"2026-06-17T02:02:17+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+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"}