The maintainers of OpenSSH have produced OpenSSH 9.2 to deal with a number of security bugs, which includes a memory protection vulnerability in the OpenSSH server (sshd).
Tracked as CVE-2023-25136, the shortcoming has been categorised as a pre-authentication double cost-free vulnerability that was introduced in version 9.1.
“This is not thought to be exploitable, and it happens in the unprivileged pre-auth system that is topic to chroot(2) and is additional sandboxed on most important platforms,” OpenSSH disclosed in its release notes on February 2, 2023.
Credited with reporting the flaw to OpenSSH in July 2022 is security researcher Mantas Mikulenas.
OpenSSH is the open up source implementation of the protected shell (SSH) protocol that gives a suite of expert services for encrypted communications around an unsecured network in a shopper-server architecture.
“The exposure happens in the chunk of memory freed two times, the ‘options.kex_algorithms,'” Qualys researcher Saeed Abbasi reported, including the issue results in a “double free of charge in the unprivileged sshd system.”
Double no cost flaws occur when a vulnerable piece of code calls the cost-free() perform – which is applied to deallocate memory blocks – twice, main to memory corruption, which, in flip, could direct to a crash or execution of arbitrary code.
“Doubly liberating memory may perhaps outcome in a create-what-in which condition, enabling an attacker to execute arbitrary code,” MITRE notes in its description of the flaw.
“Though the double-free of charge vulnerability in OpenSSH version 9.1 may perhaps elevate problems, it is critical to observe that exploiting this issue is no basic process,” Abbasi defined.
“This is because of to the protective actions put in spot by contemporary memory allocators and the sturdy privilege separation and sandboxing implemented in the impacted sshd method.”
Users are advisable to update to OpenSSH 9.2 to mitigate probable security threats.
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