VulnerabilityPublished 7 Jan 2026

CVE-2025-67364: fast-filesystem-mcp · Path Traversal: '../filedir

Affects fast-filesystem-mcpSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Jan 2026
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 26 Oct 2026.

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 or the CVSS exploit maturity 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
GitHubefforthye/fast-filesystem-mcp`pkg:github/efforthye/fast-filesystem-mcp`Other threats	Affected =3.4.0	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Immediately audit all instances of fast-filesystem-mcp version 3.4.0 in your environment and identify usage of vulnerable file operation tools such as fast_read_file.
Restrict or disable the creation and usage of symbolic links within directories accessible by these tools until a patch is available.
Implement additional path validation logic that fully resolves symbolic links to their physical paths before enforcing access controls, using secure libraries or custom code that handles symlink resolution correctly.
Employ file system monitoring to detect unusual symlink creation or access patterns indicative of exploitation attempts.
Limit permissions of processes running fast-filesystem-mcp tools to the minimum necessary, preventing access to sensitive directories even if symlink bypass occurs.
Engage with the software vendor or community to obtain patches or updates addressing this vulnerability as soon as they are released.
Consider deploying application-layer firewalls or endpoint detection solutions capable of identifying path traversal attempts.
Educate system administrators and developers about the risks of relying solely on path.resolve() for security checks and the importance of comprehensive symlink handling.

Description

fast-filesystem-mcp version 3.4.0 contains a critical path traversal vulnerability in its file operation tools including fast_read_file. This vulnerability arises from improper path validation that fails to resolve symbolic links to their actual physical paths. The safePath and isPathAllowed functions use path.resolve() which does not handle symlinks, allowing attackers to bypass directory access restrictions by creating symlinks within allowed directories that point to restricted system paths. When these symlinks are accessed through valid path references, the validation checks are circumvented, enabling access to unauthorized files.

Impact

The primary impact of CVE-2025-67364 is unauthorized access to sensitive files outside of intended directories, which can lead to data breaches, leakage of confidential information, or unauthorized modification of critical system files. For European organizations, especially those in sectors such as finance, healthcare, government, and critical infrastructure, this vulnerability could result in significant operational disruption and regulatory non-compliance under GDPR and other data protection laws. Attackers exploiting this flaw could gain access to system configuration files, credentials, or proprietary data, potentially enabling further lateral movement or privilege escalation. The vulnerability's ease of exploitation without authentication or user interaction increases the risk of automated or mass exploitation campaigns. The absence of known exploits in the wild currently limits immediate impact, but the critical nature of the flaw demands proactive mitigation to prevent future attacks. Organizations using fast-filesystem-mcp in cloud environments or shared hosting could face elevated risks due to multi-tenant exposure.

CWE-24Path Traversal: '../filedir' (opens in a new tab)
Variant weakness
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize "../" sequences that can resolve to a location that is outside of that directory.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP ASVS 4.0.3
V12.3.1 (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 7 Jan 2026, 17:12 UTC

WeaknessesCWE-24

Technical details

References

Community reviews

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