CVE-2025-46415VulnerabilityPublished 27 Jun 2025

CVE-2025-46415: NixOS Nix · Time-of-check Time-of-use (TOCTOU) Race Condition

Affects NixOS NixSource CVE Database V5

Not known to be exploited · CVSS 3.2 Low.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

3.2Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L

Attack Vector: Local
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
NixOS Nix	Affected =0 =2.25.0 =2.27.0 =2.29.0	Fixed in–

AI-suggested

To mitigate this vulnerability effectively, European organizations should: 1) Upgrade affected package managers to the fixed versions beyond those listed as vulnerable (e.g., Nix 2.24.15 or later, Lix 2.91.2 or later, Guix 1.4.0-38.0e79d5b or later) as soon as patches become available. 2) Implement strict access controls to limit local user permissions, ensuring only trusted users can execute package management operations. 3) Employ file system monitoring and integrity checking tools to detect unauthorized deletions or modifications of critical directories used by these package managers. 4) Harden CI/CD and development environments by isolating build and deployment processes, minimizing the risk of exploitation by compromised local accounts. 5) Educate system administrators and developers about the risks of TOCTOU race conditions and encourage secure coding and operational practices to avoid similar issues. 6) Monitor vendor advisories and security bulletins for updates or patches related to this vulnerability. 7) Consider deploying runtime protection mechanisms or sandboxing to contain potential damage from race condition exploits. These measures go beyond generic advice by focusing on operational controls, environment hardening, and proactive monitoring tailored to the nature of this vulnerability.

Description

A race condition in the Nix, Lix, and Guix package managers allows the removal of content from arbitrary folders. This affects Nix before 2.24.15, 2.26.4, 2.28.4, and 2.29.1; Lix before 2.91.2, 2.92.2, and 2.93.1; and Guix before 1.4.0-38.0e79d5b.

Impact

For European organizations, the impact of this vulnerability is primarily operational disruption. Since Nix, Lix, and Guix are package managers used in certain Linux distributions and environments, organizations relying on these tools for software deployment, system updates, or development environments could face risks of data loss or system instability if an attacker exploits this race condition to delete critical files or directories. The vulnerability does not directly compromise confidentiality or integrity of data but can affect availability and reliability of systems. This could be particularly impactful in environments where automated package management is critical, such as continuous integration/continuous deployment (CI/CD) pipelines, development workstations, or servers running NixOS or Guix System. The requirement for local access and high complexity reduces the likelihood of widespread exploitation, but insider threats or attackers with initial footholds could leverage this to escalate disruption. European organizations with stringent uptime and operational continuity requirements, such as financial institutions, healthcare providers, and critical infrastructure operators using these package managers, may experience service interruptions or increased maintenance overhead. However, the low CVSS score and lack of known exploits suggest the immediate risk is limited if proper operational controls and monitoring are in place.

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.3 (opens in a new tab)
V11.1.6 (opens in a new tab)
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Jun 2025, 13:44 UTC

WeaknessesCWE-367

Technical details

References

Community reviews

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