{"id":"CVE-2019-16928","kind":"vulnerability","aliases":["CVE-2019-16928"],"related":[],"title":"Exim Exim Internet Mailer: Exim Out-of-bounds Write Vulnerability","description":"Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than CVE-2019-15846. There is a heap-based buffer overflow in string_vformat in string.c involving a long EHLO command.","summary":"Exim, a widely used mail transfer agent, has an out-of-bounds write in its EHLO/string handling that lets a remote sender write past a buffer. An attacker who can reach the SMTP port can run code on the mail server, and CISA lists it as actively exploited.","severity":"critical","cvss":9.8,"epss":0.41638,"exploited":true,"exploited_at":"2022-03-03T00:00:00+00:00","products":[{"name":"Exim Exim Internet Mailer","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exim","exploited","mail-server","package","self-hosted"],"not_affected_if":["managed-hosting","no-exim-installed"],"how_to_check":"Run exim -bV to read the installed version and compare it with the fixed release in the vendor advisory.\nSee whether port 25 on the host accepts SMTP connections from the internet.","fix":"Upgrade Exim to a release that includes the vendor fix for CVE-2019-16928, following the vendor instructions named in the CISA entry.","status":"open","published_at":"2019-09-27T21:15:10+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:26:18+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-23T21:26:18Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade Exim to a release that includes the vendor fix for CVE-2019-16928, following the vendor instructions named in the CISA entry.\nunknown","reach":"internet","impact":"high","summary":"Exim, a widely used mail transfer agent, has an out-of-bounds write in its EHLO/string handling that lets a remote sender write past a buffer. An attacker who can reach the SMTP port can run code on the mail server, and CISA lists it as actively exploited.","category":"package","who_cares":["exim","self-hosted","mail-server"],"confidence":0.6,"needs_auth":"no","worst_case":"remote attacker runs code as the Exim process user","analyst_note":"Find the affected and fixed Exim version range and the exact trigger condition (for example whether it needs the EHLO or a specific option) from the NVD or Exim advisory; the signal gives no version data.","how_to_check":"Run exim -bV to read the installed version and compare it with the fixed release in the vendor advisory.\nSee whether port 25 on the host accepts SMTP connections from the internet.\nunknown","needs_analyst":true,"not_affected_if":["managed-hosting","no-exim-installed"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000506,"input_tokens":2815,"output_tokens":449,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-15846':94C '-16928':14A,17A '-2019':13A,16A,93C '4.92':81C '4.92.2':83C 'activ':78B 'agent':37B 'allow':84C 'attack':59B 'base':100C 'bound':9A,43B 'buffer':57B,101C 'cisa':74B 'code':68B,86C 'command':112C 'cve':12A,15A,92C 'differ':89C 'ehlo':111C 'ehlo/string':47B 'execut':87C 'exim':1A,2A,5A,18A,19A,22B,31B,80C 'exploit':23B,79B 'handl':48B 'heap':99C 'heap-bas':98C 'host':30B 'internet':3A,20A 'involv':108C 'let':50B 'list':75B 'long':110C 'mail':25B,35B,71B 'mail-serv':24B 'mailer':4A,21A 'out-of-bound':6A,40B 'overflow':102C 'packag':27B 'past':55B 'port':65B 'reach':62B 'remot':52B,85C 'run':67B 'self':29B 'self-host':28B 'sender':53B 'server':26B,72B 'smtp':64B 'string':104C 'string.c':107C 'transfer':36B 'use':34B 'vformat':105C 'vulner':11A,90C 'wide':33B 'write':10A,44B,54B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2019-09-27T21:15:10+00:00","kev":{"dateAdded":"2022-03-03","dueDate":"2022-03-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"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-2019-16928","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-16928","severity":null,"published_at":"2022-03-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T12:39:24+00:00","note":null},{"source":"epss","external_id":"CVE-2019-16928","url":"https://api.first.org/data/v1/epss?cve=CVE-2019-16928","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-2019-16928","url":"https://nvd.nist.gov/vuln/detail/CVE-2019-16928","severity":null,"published_at":"2019-09-27T21:15:10+00:00","modified_at":"2026-06-17T02:22:58+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"}