CVE-2026-59842
published 2026-07-21CVE-2026-59842: A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without…
PriorityP335medium5.3CVSS 3.1
AVNACLPRNUINSUCLINAN
EPSS
0.49%
41.5th percentile
A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without proper length validation, leading to an out-of-bounds heap read. This could allow a remote unauthenticated attacker to disclose small amounts of server memory.
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| libssh | libssh | — | — |
| libssh | libssh | — | — |
| redhat | enterprise_linux | — | — |
| redhat | enterprise_linux | — | — |
| redhat | enterprise_linux_for_els | — | — |
| redhat | enterprise_linux_for_eus | — | — |
| redhat | enterprise_linux_for_ibm_z_systems | — | — |
| redhat | enterprise_linux_for_ibm_z_systems | — | — |
| redhat | enterprise_linux_for_ibm_z_systems_els | — | — |
| redhat | enterprise_linux_for_ibm_z_systems_eus | — | — |
| redhat | enterprise_linux_for_power_little_endian | — | — |
| redhat | enterprise_linux_for_power_little_endian | — | — |
| redhat | enterprise_linux_for_power_little_endian_els | — | — |
| redhat | enterprise_linux_for_power_little_endian_eus | — | — |
CVSS provenance
nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
vendor_redhat3.7LOW
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VulDB
Red Hat libssh GSSAPI out-of-bounds (Nessus ID 337346)
vuldb·2026-08-18·CVSS 5.3
CVE-2026-59842 [MEDIUM] Red Hat libssh GSSAPI out-of-bounds (Nessus ID 337346)
A vulnerability was found in Red Hat libssh. It has been rated as problematic. This issue affects some unknown processing of the component GSSAPI. Performing a manipulation results in out-of-bounds read.
This vulnerability is known as CVE-2026-59842. Remote exploitation of the attack is possible. No exploit is available.
GHSA
A flaw was found in libssh.
ghsa_unreviewed·2026-07-21
CVE-2026-59842 [LOW] CWE-125 A flaw was found in libssh.
A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without proper length validation, leading to an out-of-bounds heap read. This could allow a remote unauthenticated attacker to disclose small amounts of server memory.
Red Hat
libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
vendor_redhat·2026-07-21·CVSS 3.7
CVE-2026-59842 [LOW] CWE-125 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
A flaw was found in libssh. During server-side GSSAPI key exchange, a client-supplied Curve25519 public key shorter than the expected length is copied without proper length validation, leading to an out-of-bounds heap read. This could allow a remote unauthenticated attacker to disclose small amounts of server memory.
Mitigation: Disable GSSAPIKeyExchange or remove gss-curve25519-sha256- from GSSAPIKexAlgorithms if appropriate.
Package: libssh (Red Hat Enterprise Linux 10) - Affected
Package: libssh (Red Hat Enterprise Linux 8) - Not affected
Package: libssh (Red Hat Enterprise Linux 9) - Not affected
Package: libssh (Red Hat Hardened Images) - Affected
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key [fedora-all]
bugzilla·2026-07-21·CVSS 3.7
CVE-2026-59842 [LOW] CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key [fedora-all]
CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
A flaw was found in libssh in the server-side GSSAPI Curve25519 key exchange path in src/kex-gss.c. In ssh_server_gss_kex_process_init(), a client-controlled SSH string is unpacked into client_pubkey and then copied with memcpy(..., CURVE25519_PUBKEY_SIZE) without validating ssh_string_len(client_pubkey). A remote unauthenticated client can send a short public key in SSH_MSG_KEXGSS_INIT and trigger an out-of-bounds heap read during handshake processing, disclosing
Bugzilla
CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
bugzilla·2026-07-08·CVSS 3.7
CVE-2026-59842 [LOW] CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
CVE-2026-59842 libssh: libssh: information disclosure via short GSSAPI Curve25519 public key
A flaw was found in libssh in the server-side GSSAPI Curve25519 key exchange path in src/kex-gss.c. In ssh_server_gss_kex_process_init(), a client-controlled SSH string is unpacked into client_pubkey and then copied with memcpy(..., CURVE25519_PUBKEY_SIZE) without validating ssh_string_len(client_pubkey). A remote unauthenticated client can send a short public key in SSH_MSG_KEXGSS_INIT and trigger an out-of-bounds heap read during handshake processing, disclosing small amounts of adjacent server memory.
2026-07-21
Published