Quick answers
- Is CVE-2026-59842 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-59842 being exploited in the wild.
- How severe is CVE-2026-59842?
- Low severity, with a CVSS score of 3.7, published 21 July 2026.
- Which products and versions are affected?
- Libssh unspecified.
- Is there a fix for CVE-2026-59842?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-59842 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-59842?
- Check whether you run Libssh at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A flaw was found in libssh within the server-side GSSAPI Curve25519 key exchange path in src/kex-gss.c. Specifically, in the ssh_server_gss_kex_process_init() function, a client-supplied SSH string is unpacked into client_pubkey and subsequently copied using memcpy() with a fixed CURVE25519_PUBKEY_SIZE without validating the actual length of the input string. A remote, unauthenticated attacker can exploit this by sending a short public key in an SSH_MSG_KEXGSS_INIT message, triggering an out-of-bounds heap read. This vulnerability allows for the disclosure of small amounts of adjacent server memory during the handshake process.
Affected products
- libssh libssh unspecified
- Red Hat Red Hat Enterprise Linux 10 affected
- Red Hat Red Hat Hardened Images affected
Timeline
- 2026-07-08: disclosed: Initial report in Red Hat Bugzilla
- 2026-07-21: advisory: NVD publication date