CVE-2017-16943
CRITICALEPSS 99th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
References
Related Vulnerabilities
Other CWE-416 (Use After Free) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2019-0708 | Critical | 9.8 | 100% | KEV + Ransom | - |
| CVE-2021-31166 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2015-5119 | Critical | 9.8 | 99% | KEV | - |
| CVE-2010-3962 | High | 8.1 | 96% | KEV | - |
| CVE-2015-0313 | Critical | 9.8 | 96% | KEV | Fix |
| CVE-2021-34833 | High | 7.8 | 96% | - | - |
Common questions
How do I fix CVE-2017-16943?
Upgrade exim4 on debian 11 to 4.89-12 or later.
Is CVE-2017-16943 being actively exploited?
Not that we know of. CVE-2017-16943 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 46.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 99% of all scored CVEs.
How severe is CVE-2017-16943?
CVE-2017-16943 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2017-16943 affect?
Published advisories record a fix for exim4 (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.