EUVD-2026-46176
GHSA-x94w-cg8g-g593
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
GSSAPI key exchange must be explicitly enabled (AC:H); attack is pre-authentication (PR:N) with only small, bounded memory disclosure (C:L) and no integrity or availability impact.
Primary rating from Vendor (redhat).
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Lifecycle Timeline
4DescriptionNVD
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.
AnalysisAI
Out-of-bounds heap read in libssh exposes small amounts of server memory during GSSAPI key exchange, exploitable by remote unauthenticated attackers. When a client submits a Curve25519 public key shorter than the expected 32 bytes during server-side GSSAPI key exchange, libssh copies the key without validating its length, triggering a read beyond the intended buffer boundary. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target server to be running libssh with GSSAPI key exchange support compiled in and actively enabled - this is a non-default configuration. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 3.7 (Low) accurately reflects a constrained risk profile. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A remote attacker connects to an SSH server running libssh with GSSAPI key exchange enabled and deliberately initiates a GSSAPI Curve25519 key exchange, supplying a public key shorter than the required 32 bytes. The server processes the malformed key without length validation, reads beyond the allocated heap buffer, and may return small amounts of adjacent server memory as part of the exchange. … |
| Remediation | An exact fixed libssh package version is not confirmed in the available intelligence - monitor the Red Hat Security Advisory at https://access.redhat.com/security/cve/CVE-2026-59842 and Bugzilla issue 2498168 for patch release. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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