Threats / Exim / CVE-2019-16928
CVE-2019-16928
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Exim Internet Mailer vulnerability
Exim Internet Mailer contains an out-of-bounds write vulnerability (CWE-787) enabling remote code execution. The flaw has been exploited in the wild.
Verdict
Today item — known-exploited.
An unauthenticated remote attacker can exploit this out-of-bounds write to achieve arbitrary code execution on systems running vulnerable Exim versions. Active exploitation in the wild indicates immediate risk to mail infrastructure.
CISA KEV Yes · 2022-03-034EPSS 0.41589 (verify live)5CVSS 9.8 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
1 independent public report of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03).
Probability (EPSS)
EPSS 0.41589 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) · Affected: Exim, Exim Internet Mailer. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 888 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious message or SMTP command that triggers an out-of-bounds write in Exim's memory handling.
Business
Mail server is compromised, enabling attacker to read, modify, or delete email and access internal communications.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute arbitrary code with the privileges of the Exim process to establish persistence and lateral movement.
Business
Attacker gains foothold in network infrastructure, potentially compromising connected systems and sensitive data.
3
Lateral reach — past segmentation narrative 3
Attacker
I use the compromised mail server to distribute malware, phishing campaigns, or further attacks against downstream recipients.
Business
Organization's reputation is damaged; customers and partners receive malicious content originating from trusted mail infrastructure.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05