Out-of-bounds read in libssh - CVE-2026-59842
Published: July 27, 2026
Vulnerability identifier: #VU139528
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-59842
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to out-of-bounds read in ssh_server_gss_kex_process_init when processing a GSSAPI key exchange with a malformed ephemeral Curve25519 public key. A remote attacker can send a specially crafted public key to disclose sensitive information.
Successful exploitation relies on observing whether key exchange succeeds after sending a shortened public key prefix, which may expose up to 32 bytes of adjacent heap memory.
Affected software
libssh
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
libssh (Red Hat package)
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
libssh (Red Hat package)
How to mitigate CVE-2026-59842
Install security update from vendor's website.
libssh - update to 0.12.1
libssh (Red Hat package) - update to 0.12.0-3.el10_2
libssh (Red Hat package) - update to 0.12.0-3.el10_2