CVE-2026-40556

Local file injection via world-writable XDG directory

Published Apr 28, 2026 · Updated Apr 28, 2026

Incorrect directory permissions in GNU nano 2.9.1 through 8.7.1 allow local users to write into another user's XDG hierarchy. The XDG data-directory setup passes mode 0777 when creating ~/.local, so a permissive process umask leaves it world-writable while stricter descendants are created. Exploitation requires a permissive umask and a successful local race, and the rejected source identifier no longer represents an active CVE record.

CVSS severityUnavailable
Unscored
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Incorrect directory permissions in GNU nano 2.9.1 through 8.7.1 allow local users to write into another user's XDG hierarchy. The XDG data-directory setup passes mode 0777 when creating ~/.local, so a permissive process umask leaves it world-writable while stricter descendants are created. Exploitation requires a permissive umask and a successful local race, and the rejected source identifier no longer represents an active CVE record.

The record

CVE
CVE-2026-40556
Published
Apr 28, 2026
Updated
Apr 28, 2026
Vendor
The GnuPG Project
Product
GNU nano
Classifications
CWE-732
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.9.1 <9.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The GnuPG Project · GNU nanoversion=2.9.1 <9.0

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo