CVE-2026-59846: Libssh: libssh: information disclosure via proxycommand %r username expansion

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• libssh libsshall versions
• redhat enterprise linux10.0
• redhat enterprise linux8.0
• redhat enterprise linux9.0
• redhat hardened imagesall versions

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

• Red Hat Red Hat Enterprise Linux 10

  • 0:0.12.0-3.el10_2 and laternot affected · rpm

• Red Hat Red Hat Enterprise Linux 8

  • 0:0.9.6-17.el8_10 and laternot affected · rpm
  • 0:0.9.6-17.el8_10 and laternot affected · rpm

• Red Hat Red Hat Enterprise Linux 9

  • 0:0.10.4-19.el9_8 and laternot affected · rpm
  • 0:0.10.4-19.el9_8 and laternot affected · rpm

• Red Hat Red Hat Hardened Images

  • 0.12.1-4.hum1 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2018-10933A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4.
  64This week
• CVE-2019-14889A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
  36Monitor
• CVE-2026-59851Libssh: libssh: authentication bypass via missing gssapi principal check
  35Monitor

Published before and after this one in the same product

• ← EarlierCVE-2026-59845Jul 21, 2026 · Libssh: libssh: denial of service via unchecked proxycommand fork() failure
  23Monitor
• ← EarlierCVE-2026-15370Jul 21, 2026 · Libssh: libssh: stack buffer overflow in sftp server longname construction
  29Monitor
• Later →CVE-2026-59847Jul 21, 2026 · Libssh: libssh: integrity downgrade via openssl aes-gcm tag verification
  30Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

User input is inserted as text into a shell command. The shell may interpret special characters in the input as part of the command.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1const host = req.body.host;2exec("ping -c 1 " + host, onResult);

1const host = req.body.host;2if (!/^[a-z0-9.-]{1,253}$/i.test(host)) return res.sendStatus(400);3execFile("ping", ["-c", "1", host], onResult);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.