How severe is CVE-2017-16943?

CVE-2017-16943 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2017-16943 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-16943?

CVE-2017-16943 primarily affects Exim. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2017-16943?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2017-16943 published?

CVE-2017-16943 was published on 2017-11-25 and last updated on 2026-06-17.

CVE-2017-16943

CVE-2017-16943 is a critical-severity vulnerability in Exim with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 47% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-416.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 47% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Exim
Published: 2017-11-25
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2017-16943?: 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 severe is CVE-2017-16943?: CVE-2017-16943 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2017-16943 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-16943?: CVE-2017-16943 primarily affects Exim. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-16943?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-16943 published?: CVE-2017-16943 was published on 2017-11-25 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:exim:exim:4.88:-:*:*:*:*:*:*
cpe:2.3:a:exim:exim:4.89:-:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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