EUVD-2026-47874
GHSA-cgrj-mh7v-v4c8
Severity by source
AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H
Local-only attack via crafted filename requires low-privilege account and active user interaction; high I/A from potential %n memory writes and crash; low C from stack read disclosure only.
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
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.
AnalysisAI
Format string vulnerability in GNU nano's multi-buffer error message handling allows a local low-privileged attacker to cause stack information disclosure, denial of service via crash, or potentially achieve arbitrary memory writes. The flaw (CWE-134) is triggered when a user opens multiple files at startup, one of which carries a specially crafted name containing printf format specifiers and another triggers an ALERT-level error - causing nano to misinterpret the filename as a format string. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires all of the following conditions to be simultaneously true: (1) the victim user invokes GNU nano in multi-buffer mode with multiple files at startup (e.g., `nano fileA fileB`); (2) at least one of those files triggers an ALERT-level error during nano's startup sequence - for example, a file with permissions that prevent opening or a filename that causes an internal error condition; (3) at least one filename among the opened files contains printf format specifiers (e.g., %n, %x, %s) placed by the attacker. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 6.8 Medium score accurately reflects a constrained but meaningful attack surface. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with a low-privilege local account creates a file named with embedded format specifiers (for example, a filename such as '%n%x%s%n') and places it in a directory accessible to a target user. The attacker then arranges - through social engineering, a shared project directory, or a script - for the target to open nano simultaneously with this crafted file and a second file that triggers an ALERT-level error (such as a file with permissions that cause an access error). … |
| Remediation | Monitor https://access.redhat.com/security/cve/CVE-2026-6390 for the Red Hat Security Advisory (RHSA) containing the patched nano package for your RHEL version; no exact patched package version is confirmed in available data at time of analysis. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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