CVE-2023-6918Network attack vector

Connection interruption via unchecked digest failures

Published Dec 18, 2023 · Updated Nov 21, 2025

Unchecked return value handling in libssh on Red Hat Enterprise Linux 8 and 9 allows remote attackers to interrupt SSH connections. The message-digest abstraction fails to check crypto-backend results and can dereference NULL or feed uninitialized memory into the KDF. Exploitation requires a backend digest failure in a low-memory state; mismatched derived keys cause decryption or integrity failure and terminate the connection.

CVSS severity3.7
Low
EPSS probability1.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Unchecked return value handling in libssh on Red Hat Enterprise Linux 8 and 9 allows remote attackers to interrupt SSH connections. The message-digest abstraction fails to check crypto-backend results and can dereference NULL or feed uninitialized memory into the KDF. Exploitation requires a backend digest failure in a low-memory state; mismatched derived keys cause decryption or integrity failure and terminate the connection.

The record

CVE
CVE-2023-6918
Published
Dec 18, 2023
Updated
Nov 21, 2025
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8
Classifications
CWE-252, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

5.3NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.7libsshCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-252Unchecked Return Value
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo