libgit2 up to 1.9.0 libssh2 ssh_libssh2.c gen_proto command injection

Summaryinfo

A vulnerability categorized as critical has been discovered in libgit2 up to 1.9.0. This impacts the function gen_proto of the file ssh_libssh2.c of the component libssh2. Such manipulation leads to command injection. This vulnerability is referenced as CVE-2026-5917. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in libgit2 up to 1.9.0 and classified as critical. Affected by this issue is the function gen_proto of the file ssh_libssh2.c of the component libssh2. The manipulation with an unknown input leads to a command injection vulnerability. Using CWE to declare the problem leads to CWE-77. The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. CVE summarizes:

libgit2 versions v0.27.0 through v1.9.0 built with the libssh2 SSH backend (USE_SSH=libssh2) contain a shell command injection vulnerability that allows remote attackers to execute arbitrary commands on an SSH server by supplying a repository path containing unescaped shell metacharacters such as single quotes, semicolons, or pipes. The gen_proto() function in ssh_libssh2.c inserts the repository path directly into a shell command string without escaping special characters before passing it to libssh2_channel_exec(), enabling an attacker to craft a malicious submodule URL in a .gitmodules file that, when processed during a recursive clone, causes the remote server's shell to interpret injected commands under the victim's SSH user account.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-5917 since 04/08/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/12/2026). The MITRE ATT&CK project declares the attack technique as T1202.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• libgit2

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9.0

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CPE 2.2info

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