CVE-2019-16928

Exp

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.

Published: 2019-09-27 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-16928 is rated Critical Active Threat (93.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 42.48%, 99th percentile). CISA KEV confirms active exploitation (added 2022-03-03) affecting Exim / Exim Internet Mailer. a weakness (CWE-787) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2019-16928

Name: Exim Out-of-bounds Write Vulnerability · CISA KEV detail

Exploit added: 2022-03-03

Action due: 2022-03-17

Required action: Apply updates per vendor instructions.

Public exploit references (Exploit-DB) for CVE-2019-16928

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2019-16928

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 90.31% 42.48% -47.83%
2 2026-05-30 90.39% 90.31% -0.08%
3 2026-05-14 — 90.39% —

Full EPSS history (73 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-16928

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2019-16928

OS Trackers for CVE-2019-16928

vendor priority summary link
alpine — CVE-2019-16928: 1 source package rows (exim); 13 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 6. https://security.alpinelinux.org/vuln/CVE-2019-16928
debian not yet assigned CVE-2019-16928 not yet assigned priority: Debian including 1 source packages (exim4), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-16928
gentoo high CVE-2019-16928: 1 GLSA(s) (202003-47), 1 atom(s) (mail-mta/exim); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2019-16928
redhat critical — https://access.redhat.com/security/cve/CVE-2019-16928
ubuntu medium CVE-2019-16928 medium priority: Ubuntu including 1 source packages (exim4), 5 status rows across 5 suites (bionic, disco, trusty, upstream, xenial): not-affected 3, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2019-16928

Affected software / configurations for CVE-2019-16928

Vendor Product Version Raw CPE
exim exim >= 4.92, <= 4.92.2 cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*
canonical ubuntu_linux 19.04 cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
fedoraproject fedora 29 cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
fedoraproject fedora 30 cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*

References for CVE-2019-16928

URL Tags
http://www.openwall.com/lists/oss-security/2019/09/28/1 Exploit Mailing List Mitigation Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/09/28/2 Exploit Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/09/28/3 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/09/28/4 Mailing List Third Party Advisory
https://bugs.exim.org/show_bug.cgi?id=2449 Issue Tracking Patch Vendor Advisory
https://git.exim.org/exim.git/commit/478effbfd9c3cc5a627fc671d4bf94d13670d65f Patch
https://lists.exim.org/lurker/message/20190927.032457.c1044d4c.en.html Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EED7HM3MFIBAP5OIMJAFJ35JAJABTVSC/ Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T3TJW4HPYH3O5HZCWGD6NSHTEBTTAPDC/ Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UY6HPRW7MR3KBQ5JFHH6OXM7YCZBJCOB/ Release Notes
https://seclists.org/bugtraq/2019/Sep/60 Mailing List Third Party Advisory
https://security.gentoo.org/glsa/202003-47 Third Party Advisory
https://usn.ubuntu.com/4141-1/ Third Party Advisory
https://www.debian.org/security/2019/dsa-4536 Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-16928 US Government Resource
cvelogic Threat Intelligence