Description
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.
Published: 2026-07-21
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability is a heap read caused by copying a Curve25519 public key that is shorter than expected during server-side GSSAPI key exchange in libssh. The flaw allows a remote unauthenticated attacker to read a small portion of server memory, potentially exposing sensitive data. This weakness is categorized as CWE-125, out-of-bounds read.

Affected Systems

The issue affects Red Hat Enterprise Linux 8, 9, 10 and Red Hat Hardened Images, which ship the vulnerable version of libssh. The specific product is the libssh library embedded in these operating systems.

Risk and Exploitability

The CVSS score of 3.7 indicates low severity, and the EPSS score of less than 1% suggests a very low likelihood of exploitation. The vulnerability is not listed in CISA’s KEV catalog. Attackers would need network access to establish an SSH session and trigger the vulnerable GSSAPI key exchange; no local privileges are required.

Generated by OpenCVE AI on July 30, 2026 at 17:55 UTC.

Remediation

Vendor Workaround

Disable GSSAPIKeyExchange or remove gss-curve25519-sha256- from GSSAPIKexAlgorithms if appropriate.

OpenCVE Recommended Actions

  • Apply the Red Hat security update RHSA‑2026:42922 that contains the libssh fix
  • If an immediate patch is not possible, disable GSSAPI key exchange in sshd_config by setting GSSAPIKeyExchange no
  • Remove gss‑curve25519‑sha256‑ from GSSAPIKexAlgorithms to prevent the vulnerable key exchange algorithm

Generated by OpenCVE AI on July 30, 2026 at 17:55 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Mon, 27 Jul 2026 23:30:00 +0000

Type Values Removed Values Added
First Time appeared Libssh
Libssh libssh
Redhat hardened Images
Vendors & Products Libssh
Libssh libssh
Redhat hardened Images

Wed, 22 Jul 2026 20:00:00 +0000

Type Values Removed Values Added
References

Wed, 22 Jul 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 22 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Low

Tue, 21 Jul 2026 11:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Libssh: libssh: information disclosure via short gssapi curve25519 public key
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Weaknesses CWE-125
CPEs cpe:/a:redhat:hummingbird:1
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'}

Subscriptions

Libssh Libssh
Redhat Enterprise Linux Hardened Images Hummingbird
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-07-22T19:07:19.005Z

Reserved: 2026-07-07T15:40:24.560Z

Link: CVE-2026-59842

cve-icon Vulnrichment

Updated: 2026-07-22T14:01:03.020Z

cve-icon NVD

Status : Analyzed

Published: 2026-07-21T12:18:57.727

Modified: 2026-07-30T13:13:06.720

Link: CVE-2026-59842

cve-icon Redhat

Severity : Low

Publid Date: 2026-07-21T11:03:52Z

Links: CVE-2026-59842 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-30T18:00:15Z

Weaknesses