How severe is CVE-2018-16851?

CVE-2018-16851 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-16851 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-16851?

CVE-2018-16851 primarily affects Samba. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-16851?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-16851 published?

CVE-2018-16851 was published on 2018-11-28 and last updated on 2026-06-17.

CVE-2018-16851

CVE-2018-16851 is a medium-severity vulnerability in Samba with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Samba
Published: 2018-11-28
Last modified: 2026-06-17

Description

Samba from version 4.0.0 and before versions 4.7.12, 4.8.7, 4.9.3 is vulnerable to a denial of service. During the processing of an LDAP search before Samba's AD DC returns the LDAP entries to the client, the entries are cached in a single memory object with a maximum size of 256MB. When this size is reached, the Samba process providing the LDAP service will follow the NULL pointer, terminating the process. There is no further vulnerability associated with this issue, merely a denial of service.

Frequently asked questions

What is CVE-2018-16851?: Samba from version 4.0.0 and before versions 4.7.12, 4.8.7, 4.9.3 is vulnerable to a denial of service. During the processing of an LDAP search before Samba's AD DC returns the LDAP entries to the client, the entries are cached in a single memory object with a maximum size of 256MB. When this size is reached, the Samba process providing the LDAP service will follow the NULL pointer, terminating the process. There is no further vulnerability associated with this issue, merely a denial of service.
How severe is CVE-2018-16851?: CVE-2018-16851 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-16851 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-16851?: CVE-2018-16851 primarily affects Samba. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-16851?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-16851 published?: CVE-2018-16851 was published on 2018-11-28 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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