CVE-2023-6918: Libssh: missing checks for return values for digests
A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. The return values from these were not properly checked, which could cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures, terminating the connection.
Other sources
libssh is vulnerable to a denial of service, caused by an unchecked return value flaw for the abstract layer for message digest (MD) operations. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
— IBM
The libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends.
The return values from these were not properly checked, which could cause in low-memory situations failures, NULL dereferences, crashes or at worst usage of the uninitialized memory as an input for the KDF.
In this case, non-matching keys will result in decryption/integrity failures, terminating connection.
— Red Hat
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2023-6918?
CVE-2023-6918 has a high severity rating due to potential denial of service risks from unhandled return values.
How do I fix CVE-2023-6918?
To fix CVE-2023-6918, update libssh to the latest versions specifically 0.9.8-0+deb11u1, 0.10.6-0+deb12u1, or 0.11.1-1.
What software is affected by CVE-2023-6918?
CVE-2023-6918 affects libssh versions below 0.10.6, various IBM MQ Operator releases, and specific versions of Red Hat and Debian distributions.
What can happen if CVE-2023-6918 is exploited?
Exploitation of CVE-2023-6918 can lead to low memory situations, program crashes, and potential application downtime.
Is my version of libssh vulnerable to CVE-2023-6918?
If you are running libssh versions prior to 0.10.6 or within the affected ranges listed, your version is vulnerable to CVE-2023-6918.