CVE-2026-64846Hinoki check available

Arbitrary file truncation via symlink race

Published Aug 20, 2026 · Updated Aug 20, 2026

Symlink race in the LocalStore restore path in Nix before 2.35.0 allows local users to truncate files outside the sandbox. During restore, writeFile can open a path with O_TRUNC after a final symlink is swapped, following that symlink instead of enforcing FinalSymlink::DontFollow. Exploitation requires the recursive-nix experimental feature, a malicious derivation, and winning the race, and it yields only empty-file creation or truncation with nix or nix-daemon permissions.

CVSS severity2.8
Low
EPSS probability0.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Symlink race in the LocalStore restore path in Nix before 2.35.0 allows local users to truncate files outside the sandbox. During restore, writeFile can open a path with O_TRUNC after a final symlink is swapped, following that symlink instead of enforcing FinalSymlink::DontFollow. Exploitation requires the recursive-nix experimental feature, a malicious derivation, and winning the race, and it yields only empty-file creation or truncation with nix or nix-daemon permissions.

The record

CVE
CVE-2026-64846
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
NixOS
Product
Nix
Classifications
CWE-367, CWE-61
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=< 2.35.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

NixOS · Nixversion=< 2.35.0

Published CVSS scores

2.8GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N

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-367Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-61UNIX Symbolic Link (Symlink) Following

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

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Your stack

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