GHSA-9G7J-RCQF-CPCX
Vulnerability from github – Published: 2026-04-28 15:30 – Updated: 2026-04-29 09:30GNU nano creates the user’s ~/.local directory with overly permissive permissions when the directory does not exist yet. On first use of features requiring Cross-Desktop Group (XDG) data storage, nano explicitly requests directory mode 0777, making the directory world‑writable in environments where the process umask does not sufficiently restrict permissions. In systems with a relaxed or zero umask, such as container environments, CI/CD runners, embedded systems, or user shells configured with umask 000, this results in ~/.local being created as world‑writable. A local attacker can exploit a race window between nano’s creation of ~/.local and its subsequent creation of more restrictive subdirectories to write attacker‑controlled files into the victim’s XDG directory hierarchy.
This problem was fixed in nano version 9.0
{
"affected": [],
"aliases": [
"CVE-2026-40556"
],
"database_specific": {
"cwe_ids": [
"CWE-732"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-28T15:16:30Z",
"severity": "LOW"
},
"details": "GNU nano creates the user\u2019s ~/.local directory with overly permissive permissions when the directory does not exist yet. On first use of features requiring Cross-Desktop Group (XDG) data storage, nano explicitly requests directory mode 0777, making the directory world\u2011writable in environments where the process umask does not sufficiently restrict permissions.\nIn systems with a relaxed or zero umask, such as container environments, CI/CD runners, embedded systems, or user shells configured with umask 000, this results in ~/.local being created as world\u2011writable. A local attacker can exploit a race window between nano\u2019s creation of ~/.local and its subsequent creation of more restrictive subdirectories to write attacker\u2011controlled files into the victim\u2019s XDG directory hierarchy.\n\nThis problem was fixed in nano version 9.0",
"id": "GHSA-9g7j-rcqf-cpcx",
"modified": "2026-04-29T09:30:23Z",
"published": "2026-04-28T15:30:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40556"
},
{
"type": "WEB",
"url": "https://cert.pl/en/posts/2026/04/CVE-2026-40556"
},
{
"type": "WEB",
"url": "https://cgit.git.savannah.gnu.org/cgit/nano.git/commit/?id=cb43493e"
},
{
"type": "WEB",
"url": "https://www.nano-editor.org"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Confirmed: The vulnerability has been validated from an analyst's perspective.
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- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.