CVE-2026-59844 Red Hat CVE debrief

Who should care

Users of libssh SFTP servers, system administrators, security teams, and operators managing affected deployments should be aware of this vulnerability and take steps to mitigate it. Reviewing compensating controls and monitoring for suspicious activity is recommended while patches are applied. Additionally, security teams should ensure that incident response plans are updated to address potential exploitation of this vulnerability.

Technical summary

The vulnerability is caused by the lack of proper input validation in the libssh SFTP server. An attacker can exploit this vulnerability by issuing SSH_FXP_READ requests with an arbitrarily large length, causing the server to allocate excessive memory and potentially exhaust it through repeated requests. This could lead to denial-of-service conditions. Affected users should apply vendor patches or limit the length of SSH_FXP_READ requests. Implementing additional security measures, such as monitoring for suspicious activity and enhancing network defenses, can help mitigate the risk.

Defensive priority

Medium

Recommended defensive actions

• Apply the vendor patch
• Limit the length of SSH_FXP_READ requests
• Monitor for suspicious activity
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions and retest remediated assets
• Perform an exposure review for affected systems

Evidence notes

The CVE record was published on 2026-07-21T12:18:57.973Z and was last modified on 2026-07-22T20:17:03.443Z. The NVD entry is currently Undergoing Analysis. Evidence is limited to CVE and NVD details. Defenders should verify vendor guidance and affected scope. Additional review of vendor advisories and security bulletins is recommended to understand the full impact and to identify any potential mitigations or patches. Users should also monitor for any updates to the CVE record and NVD entry for further information.

Official resources