Is CVE-2016-9963 in the CISA KEV catalog?

No. CVE-2016-9963 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-9963?

CVE-2016-9963 has a CVSS v3 base score of 5.9 (MEDIUM).

What is the EPSS score for CVE-2016-9963?

CVE-2016-9963 has an EPSS score of 3.10% (86th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-9963?

Upgrade exim4 on debian 11 to 4.88~RC6-2 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2016-9963

MEDIUMEPSS 86th pctl

5.9

CVSS v3

NVD

Description

Exim before 4.87.1 might allow remote attackers to obtain the private DKIM signing key via vectors related to log files and bounce messages.

CWE-320

How to fix

Remediation Available

exim4Debian

Fixed in:4.88~RC6-2CVE-2016-9963

exim4Ubuntu

Fixed in:4.82-3ubuntu2.2USN-3164-1

Fixed in:4.86.2-2ubuntu2.1USN-3164-1

exim4-daemon-heavyUbuntu

Fixed in:4.82-3ubuntu2.2USN-3164-1

Fixed in:4.86.2-2ubuntu2.1USN-3164-1

exim4-daemon-lightUbuntu

Fixed in:4.82-3ubuntu2.2USN-3164-1

Fixed in:4.86.2-2ubuntu2.1USN-3164-1

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

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

3.10%probability of exploitation in 30 days

86thpercentile

Elevated risk: more likely to be exploited than 86% of all known CVEs.

References

Vendor Advisory2

Third-Party Advisory4

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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.