CVE-2023-51767

CVE-2023-51767 is a high-severity vulnerability in Openbsd Openssh with a CVSS 3.x base score of 7.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

• Severity: High (CVSS 3.x base score 7.0)
• EPSS exploit prediction: 1% (47th percentile)
• Actively exploited: Not listed in CISA KEV
• Affected product: Openbsd Openssh
• Published: 2023-12-24
• Last modified: 2026-06-17

Description

OpenSSH through 10.0, when common types of DRAM are used, might allow row hammer attacks (for authentication bypass) because the integer value of authenticated in mm_answer_authpassword does not resist flips of a single bit. NOTE: this is applicable to a certain threat model of attacker-victim co-location in which the attacker has user privileges. NOTE: this is disputed by the Supplier, who states "we do not consider it to be the application's responsibility to defend against platform architectural weaknesses."

Frequently asked questions

What is CVE-2023-51767?

OpenSSH through 10.0, when common types of DRAM are used, might allow row hammer attacks (for authentication bypass) because the integer value of authenticated in mm_answer_authpassword does not resist flips of a single bit. NOTE: this is applicable to a certain threat model of attacker-victim co-location in which the attacker has user privileges. NOTE: this is disputed by the Supplier, who states "we do not consider it to be the application's responsibility to defend against platform architectural weaknesses."

How severe is CVE-2023-51767?

CVE-2023-51767 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-51767 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-51767?

CVE-2023-51767 primarily affects Openbsd Openssh. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-51767?

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-2023-51767 published?

CVE-2023-51767 was published on 2023-12-24 and last updated on 2026-06-17.

References

• https://access.redhat.com/security/cve/CVE-2023-51767
• https://arxiv.org/abs/2309.02545
• https://bugzilla.redhat.com/show_bug.cgi?id=2255850
• https://github.com/openssh/openssh-portable/blob/8241b9c0529228b4b86d88b1a6076fb9f97e4a99/auth-passwd.c#L77
• https://github.com/openssh/openssh-portable/blob/8241b9c0529228b4b86d88b1a6076fb9f97e4a99/monitor.c#L878
• https://security.netapp.com/advisory/ntap-20240125-0006/
• https://ubuntu.com/security/CVE-2023-51767
• https://www.openwall.com/lists/oss-security/2025/09/22/1
• http://www.openwall.com/lists/oss-security/2025/09/22/1
• http://www.openwall.com/lists/oss-security/2025/09/22/2
• http://www.openwall.com/lists/oss-security/2025/09/23/1
• http://www.openwall.com/lists/oss-security/2025/09/23/3
• http://www.openwall.com/lists/oss-security/2025/09/23/4
• http://www.openwall.com/lists/oss-security/2025/09/23/5
• http://www.openwall.com/lists/oss-security/2025/09/24/4
• http://www.openwall.com/lists/oss-security/2025/09/24/7
• http://www.openwall.com/lists/oss-security/2025/09/25/2
• http://www.openwall.com/lists/oss-security/2025/09/25/6
• http://www.openwall.com/lists/oss-security/2025/09/26/2
• http://www.openwall.com/lists/oss-security/2025/09/26/4
• http://www.openwall.com/lists/oss-security/2025/09/27/1
• http://www.openwall.com/lists/oss-security/2025/09/27/2
• http://www.openwall.com/lists/oss-security/2025/09/27/3
• http://www.openwall.com/lists/oss-security/2025/09/27/4
• http://www.openwall.com/lists/oss-security/2025/09/27/5
• http://www.openwall.com/lists/oss-security/2025/09/27/6
• http://www.openwall.com/lists/oss-security/2025/09/27/7
• http://www.openwall.com/lists/oss-security/2025/09/28/7
• http://www.openwall.com/lists/oss-security/2025/09/29/1
• http://www.openwall.com/lists/oss-security/2025/09/29/4

Affected products (4)

• cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Openbsd Openssh

• CVE-2003-0786 — Critical (CVSS 10.0): The SSH1 PAM challenge response authentication in OpenSSH 3.7.1 and 3.7.1p1, when Privilege Separation is disabled,…
• CVE-2003-0693 — Critical (CVSS 10.0): A "buffer management error" in buffer_append_space of buffer.c for OpenSSH before 3.7 may allow remote attackers to…
• CVE-2002-0640 — Critical (CVSS 10.0): Buffer overflow in sshd in OpenSSH 2.3.1 through 3.3 may allow remote attackers to execute arbitrary code via a large…
• CVE-2001-0144 — Critical (CVSS 10.0): CORE SDI SSH1 CRC-32 compensation attack detector allows remote attackers to execute arbitrary commands on an SSH…
• CVE-2000-0999 — Critical (CVSS 10.0): Format string vulnerabilities in OpenBSD ssh program (and possibly other BSD-based operating systems) allow attackers…
• CVE-2000-0525 — Critical (CVSS 10.0): OpenSSH does not properly drop privileges when the UseLogin option is enabled, which allows local users to execute…

All CVEs affecting Openbsd Openssh →

Threat intelligence

Threat-intel indicators referencing this CVE:

• 152.32.208.73 (ipv4-addr)
• 152.32.217.163 (ipv4-addr)
• 152.32.204.21 (ipv4-addr)
• 152.32.145.49 (ipv4-addr)
• 104.218.164.192 (ipv4-addr)
• 165.154.162.193 (ipv4-addr)
• 165.154.11.210 (ipv4-addr)
• 152.32.207.42 (ipv4-addr)