CVE-2026-59846 Libssh: libssh: information disclosure via proxycommand %r username expansion
A malicious username in libssh ProxyCommand can inject shell metacharacters, leading to environment variable exposure and potential code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-59846?
CVE-2026-59846 is a low-severity command injection vulnerability in Redhat Enterprise Linux, published on 21 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
A flaw was found in libssh. A malicious username expanded through %r in ProxyCommand handling can inject shell metacharacters, exposing environment variables and causing unintended shell behavior.
Which versions are affected by CVE-2026-59846?
It affects 3 products.
Products include Libssh Libssh, Redhat Enterprise Linux, Redhat Hardened Images.
How do I fix CVE-2026-59846?
Apply the vendor's patch.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-59846 being exploited?
There is no known exploitation of CVE-2026-59846 in the wild and no public exploit code.
Other vulnerabilities in Redhat Enterprise Linux
- CVE-2026-59851 Libssh: libssh: authentication bypass via missing gssapi principal check
- CVE-2025-5987 Libssh: invalid return code for chacha20 poly1305 with openssl backend
- CVE-2025-14821 Libssh: libssh: insecure default configuration leads to local man-in-the-middle attacks on windows
- CVE-2012-4560 Memory corruption in n/a
- CVE-2012-4562 Integer overflow in n/a
Sources
Also known as BELL-CVE-2026-59846, DEBIAN-CVE-2026-59846, ECHO-689c-0cb6-4ae0, GHSA-fvwj-j79q-57v7, UBUNTU-CVE-2026-59846.