CVE-2017-16943

Exp

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via vectors involving BDAT commands.

Published: 2017-11-25 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-16943 is rated High Exploit Risk (83.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 46.71%, 99th percentile). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2017-16943

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-2017-16943

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 74.53% 46.71% -27.82%
2 2026-05-26 77.24% 74.53% -2.72%
3 2026-05-22 — 77.24% —

Full EPSS history (54 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-16943

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/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]
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-2017-16943

OS Trackers for CVE-2017-16943

vendor priority summary link
alpine — CVE-2017-16943: 1 source package rows (exim); 7 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 0. https://security.alpinelinux.org/vuln/CVE-2017-16943
debian not yet assigned CVE-2017-16943 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-2017-16943
gentoo high CVE-2017-16943: 1 GLSA(s) (201803-01), 1 atom(s) (mail-mta/exim); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2017-16943
redhat critical — https://access.redhat.com/security/cve/CVE-2017-16943
ubuntu high CVE-2017-16943 high priority: Ubuntu including 1 source packages (exim4), 5 status rows across 5 suites (artful, trusty, upstream, xenial, zesty): not-affected 2, released 2, needs-triage 1. https://ubuntu.com/security/CVE-2017-16943

Affected software / configurations for CVE-2017-16943

Vendor Product Version Raw CPE
exim exim 4.88 cpe:2.3:a:exim:exim:4.88:-:*:*:*:*:*:*
exim exim 4.89 cpe:2.3:a:exim:exim:4.89:-:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2017-16943

URL Tags
http://openwall.com/lists/oss-security/2017/11/25/1 Mailing List
http://openwall.com/lists/oss-security/2017/11/25/2 Mailing List
http://openwall.com/lists/oss-security/2017/11/25/3 Mailing List
http://www.openwall.com/lists/oss-security/2021/05/04/7
http://www.securitytracker.com/id/1039872 Third Party Advisory VDB Entry
https://bugs.exim.org/show_bug.cgi?id=2199 Exploit Issue Tracking
https://git.exim.org/exim.git/commit/4090d62a4b25782129cc1643596dc2f6e8f63bde Patch
https://git.exim.org/exim.git/commitdiff/4e6ae6235c68de243b1c2419027472d7659aa2b4 Patch
https://github.com/LetUsFsck/PoC-Exploit-Mirror/tree/master/CVE-2017-16944 Exploit
https://lists.exim.org/lurker/message/20171125.034842.d1d75cac.en.html Mailing List
https://www.debian.org/security/2017/dsa-4053 Third Party Advisory
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