CVE-2026-6390 Red Hat CVE debrief

Who should care

Users of GNU nano who open multiple files at startup should be aware of this vulnerability. An attacker could exploit this flaw to disclose stack information, cause a denial of service, or potentially perform arbitrary memory writes. Operators, platform administrators, vulnerability management teams, and security teams should review and address this vulnerability.

Technical summary

A flaw was found in GNU nano's multi-buffer error message handling. When a user opens multiple files at startup and one triggers an ALERT-level error, a specially crafted filename containing printf format specifiers can be reinterpreted. This format string vulnerability may allow an attacker to achieve stack information disclosure, cause a denial of service (crash), or potentially perform arbitrary memory writes. The vulnerability affects GNU nano installations where users open multiple files at startup.

Defensive priority

Medium priority should be given to patching GNU nano installations, especially in environments where users open multiple files at startup. Defenders should focus on applying patches, restricting user access, and monitoring logs for suspicious activity.

Recommended defensive actions

• Apply the patch for GNU nano to fix the multi-buffer error message handling flaw
• Restrict user access to opening multiple files at startup
• Monitor GNU nano logs for suspicious activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-23T05:16:38.360Z and has not been modified since then. The NVD entry is currently being reviewed. Evidence is limited to CVE and NVD details. Defenders should verify GNU nano multi-buffer error handling patches and user access controls.

Official resources