Medium [CVE-2026-6390] GNU nano: Arbitrary memory writes, information disclosure, or denial of service via format string vulnerability in error handling.
This medium-severity Red Hat Linux advisory covers CVE-2026-6390 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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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 nano versions 5.7 through 8.7 when compiled with multi-buffer support and without the NANO_TINY option.
Red Hat severity: Moderate — CVSS 6.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H). Weakness: CWE-134.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: nano.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 16 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 16 days ago·verify at source
Mitigation checklist
- Users should avoid opening untrusted files with GNU nano, especially those with filenames containing printf format specifiers (e.g., %s, %p, %n). This operational control helps prevent the exploitation of the format string vulnerability, which relies on specific filename content and error conditions during multi-buffer usage.
Official advisory · high-confidence parse· fetched 16 days ago·verify at source
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