CVE-2023-22742: libgit2 fails to verify SSH keys by default

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-01-20 · updated 2026-06-17
Weakness: CWE-347

Description

libgit2 is a cross-platform, linkable library implementation of Git. When using an SSH remote with the optional libssh2 backend, libgit2 does not perform certificate checking by default. Prior versions of libgit2 require the caller to set the `certificate_check` field of libgit2's `git_remote_callbacks` structure - if a certificate check callback is not set, libgit2 does not perform any certificate checking. This means that by default - without configuring a certificate check callback, clients will not perform validation on the server SSH keys and may be subject to a man-in-the-middle attack. Users are encouraged to upgrade to v1.4.5 or v1.5.1. Users unable to upgrade should ensure that all relevant certificates are manually checked.

Affected products

libgit2: before 1.4.5; 1.5.0 — fixed in 1.4.5

How to fix

Upgrade to a fixed version: libgit2 1.4.5. Check the vendor advisory for mitigations.

References

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