How severe is CVE-2016-6515?

CVE-2016-6515 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-6515 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6515?

CVE-2016-6515 primarily affects Openbsd Openssh. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6515?

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

When was CVE-2016-6515 published?

CVE-2016-6515 was published on 2016-08-07 and last updated on 2026-06-17.

CVE-2016-6515

CVE-2016-6515 is a high-severity vulnerability in Openbsd Openssh with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 59% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 59% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Openbsd Openssh
Published: 2016-08-07
Last modified: 2026-06-17

Description

The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which allows remote attackers to cause a denial of service (crypt CPU consumption) via a long string.

Frequently asked questions

What is CVE-2016-6515?: The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which allows remote attackers to cause a denial of service (crypt CPU consumption) via a long string.
How severe is CVE-2016-6515?: CVE-2016-6515 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-6515 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6515?: CVE-2016-6515 primarily affects Openbsd Openssh. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6515?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-6515 published?: CVE-2016-6515 was published on 2016-08-07 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:openbsd:openssh:*:p2:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:24:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

60.166.8.174 (ipv4-addr)
60.166.31.198 (ipv4-addr)
183.66.149.42 (ipv4-addr)
151.237.115.208 (ipv4-addr)
41.219.149.74 (ipv4-addr)
175.203.199.118 (ipv4-addr)
218.146.45.68 (ipv4-addr)
67.197.111.225 (ipv4-addr)