# CVE-2026-6390: Nano: gnu nano: arbitrary memory writes, information disclosure, or denial of service via format string vulnerability in error handling.

CVE-2026-6390 is fixed in 2 products on 1 platform, first by nano 6.2-1ubuntu0.2, released June 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-6390
- Priority: Routine
- CVSS: 6.8 (Moderate)
- EPSS: 0.0015
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 22, 2026
- Weakness: Use of Externally-Controlled Format String
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-6390

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nano Debian 14 | 9.0-1 | [DEBIAN-CVE-2026-6390](https://patchblox.com/security/data/fix/linux/debian-cve-2026-6390.md) | Aug 8, 2026 |
| Linux | nano Ubuntu 22.04.1 LTS (jammy) | 6.2-1ubuntu0.2 | [nano 6.2-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-nano-6.2-1ubuntu0.2.md) | Jun 24, 2026 |
| Linux | nano Ubuntu 24.04.5 LTS (noble) | 7.2-2ubuntu0.2 | [nano 7.2-2ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-nano-7.2-2ubuntu0.2.md) | Jun 24, 2026 |
| Linux | nano Ubuntu 25.10 (questing) | 8.4-1ubuntu0.1 | [nano 8.4-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-nano-8.4-1ubuntu0.1.md) | Jun 24, 2026 |
| Linux | nano Ubuntu 26.04.1 LTS (resolute) | 8.7.1-1ubuntu0.1 | [nano 8.7.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-nano-8.7.1-1ubuntu0.1.md) | Jul 22, 2026 |
| Linux | nano-tiny Ubuntu 22.04.1 LTS (jammy) | 6.2-1ubuntu0.2 | [nano-tiny 6.2-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-nano-tiny-6.2-1ubuntu0.2.md) | Jun 24, 2026 |
| Linux | nano-tiny Ubuntu 24.04.5 LTS (noble) | 7.2-2ubuntu0.2 | [nano-tiny 7.2-2ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-nano-tiny-7.2-2ubuntu0.2.md) | Jun 24, 2026 |
| Linux | nano-tiny Ubuntu 25.10 (questing) | 8.4-1ubuntu0.1 | [nano-tiny 8.4-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-nano-tiny-8.4-1ubuntu0.1.md) | Jun 24, 2026 |
| Linux | nano-tiny Ubuntu 26.04.1 LTS (resolute) | 8.7.1-1ubuntu0.1 | [nano-tiny 8.7.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-nano-tiny-8.7.1-1ubuntu0.1.md) | Jul 22, 2026 |

---

Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.