CVE-2026-40526

Executive Summary

CVE-2026-40526 is an unpatched path traversal vulnerability in the Volmarg Personal Management System that allows authenticated attackers with low-privilege access to read arbitrary files from the underlying server filesystem. The flaw resides in the /public/get-file/{path} endpoint, where the path route parameter is passed directly to file_get_contents() without validation or canonicalization against a permitted base directory. An authenticated attacker can supply absolute filesystem paths (e.g., /etc/passwd, /var/www/html/config.php) to retrieve sensitive data accessible to the PHP-FPM worker process. The vulnerability carries a CVSS score of 6.5 (High confidentiality impact, no integrity or availability impact), requires low privileges, and has no known public exploit, no CISA KEV listing, and no patch available as of the latest assessment.

Technical Analysis

The vulnerability class is CWE-22 (Improper Limitation of a Pathname to a Restricted Directory — Path Traversal). The NVD description indicates that the Volmarg Personal Management System implements an endpoint at /public/get-file/{path} intended to serve files to authenticated users. The server-side handler retrieves the path route parameter and passes it directly to PHP's file_get_contents() function without canonicalizing the input against a permitted base directory.

Vulnerability Mechanism:

The core flaw is the absence of input canonicalization and base-directory confinement. In a secure implementation, the application would:

1. Receive the user-supplied path parameter.
2. Resolve it to an absolute canonical path (e.g., via realpath()).
3. Verify that the resolved path begins with the intended base directory (e.g., the user's file storage directory).
4. Only then invoke file_get_contents().

In this vulnerable implementation, step 3 is missing entirely. Because file_get_contents() in PHP accepts absolute filesystem paths (e.g., /etc/passwd, /proc/self/environ, /var/www/.env) without any traversal sequences (../), the attacker does not even need to use directory traversal patterns. The direct pass-through of the route parameter means that any absolute path the attacker controls is read verbatim.

Attack Surface:

• Authentication Requirement: The attacker must be authenticated (CVSS PR:L — Low). This means the attacker needs a valid account, even with the most limited role/permissions.
• Network Exposure: The endpoint is HTTP-accessible (AV:N — Network), so the application must be reachable over the network.
• No User Interaction: The attack requires no victim interaction (UI:N).
• No Complexity Barriers: The attack complexity is low (AC:L) — no special conditions or race conditions required.

Impact Scope:

The confidentiality impact is High (C:H). The PHP-FPM worker process typically runs under the web server user (e.g., www-data or nobody), meaning the attacker can read any file that this user account can access. This commonly includes:

• PHP application source code (revealing database credentials, API keys, hardcoded secrets).
• Configuration files (.env, config.php, database connection strings).
• Operating system files (/etc/passwd, /etc/shadow if readable by the web user — unlikely but possible in misconfigured environments).
• Log files, session files, and other users' uploaded documents within the application's storage.
• /proc/ filesystem entries that may expose process environment variables.

Notably absent: There is no integrity or availability impact (I:N, A:N). This is a pure information disclosure vulnerability.

Exploitation Scenarios

Note: No public PoC or exploit code exists for this CVE at the time of writing. The following attack chain is inferred from the vulnerability class (absolute-path read via file_get_contents()) and the NVD description. No specific payload strings or implementation details beyond those in the NVD description are assumed.

Step 1 — Reconnaissance / Target Identification: An attacker first identifies instances of the Volmarg Personal Management System exposed to the internet. This can be done via:

• Shodan/Censys queries targeting HTTP headers, favicon hashes, or page titles associated with the application.
• Google dorking for distinctive phrases or file paths from the application.
• Scanning for applications that expose the /public/get-file/ endpoint pattern.

Step 2 — Authentication Acquisition: Since the vulnerability requires an authenticated session (PR:L), the attacker must obtain valid credentials. Methods include:

• Registering a new account if self-registration is enabled.
• Credential stuffing using leaked password databases (if the application lacks rate limiting).
• Social engineering or phishing against legitimate users.
• Exploiting other vulnerabilities (if any) in the authentication mechanism.

Step 3 — Triggering the Flaw: With a valid session token/cookie, the attacker crafts an HTTP GET request to the vulnerable endpoint with an absolute filesystem path as the route parameter. For example, the request would take the form:

GET /public/get-file//etc/passwd HTTP/1.1
Host: target.example.com
Cookie: [session_cookie]

Or, if the application framework maps the route parameter literally:

GET /public/get-file/etc/passwd HTTP/1.1

The key characteristic is that the path supplied does not contain ../ traversal sequences — it is an absolute path beginning with /. The application passes this value verbatim to file_get_contents(), which reads the specified file and returns its contents in the HTTP response body.

Step 4 — Post-Exploitation Impact: Once the attacker confirms the vulnerability works, they can systematically extract:

• Application source code — revealing database credentials, encryption keys, third-party API keys, and other hardcoded secrets.
• Configuration files — such as .env or config.php that may contain database hostnames, usernames, and passwords.
• OS-level files — /etc/passwd (user enumeration), /etc/hostname, /etc/shadow (in rare misconfigurations where the web user can read it).
• Other users' data — uploaded documents, private messages, or any files within the web root that the web server user can access.

This information disclosure can be leveraged for lateral movement, further exploitation of internal services (using leaked database credentials), or supply-chain compromise if internal secrets are exposed.

Impact Assessment

Affected Systems: All deployments of the Volmarg Personal Management System that expose the /public/get-file/{path} endpoint and have not applied any (nonexistent) patch. Because the patch status is 0/4 — meaning no patch evidence from any tracked source — all current versions are presumed vulnerable.

Blast Radius:

• Direct victims: Organizations running Volmarg Personal Management System as a personal or small-team productivity tool.
• Indirect victims: Users whose personal data, uploaded files, or credentials are stored within the application and are now exposed.
• Downstream impact: Leaked database credentials or application secrets may grant access to other internal systems (database servers, email, cloud services).

Business Impact:

• Regulatory violations (GDPR, HIPAA, PCI-DSS) if personal or financial data is exposed.
• Reputational damage from data breach disclosure.
• Potential account takeover if session files or password hashes are readable.

Detection Guidance

The following detection rules are designed to identify exploitation attempts against CVE-2026-40526. They focus on the distinctive request patterns — authenticated GET requests to /public/get-file/ with absolute paths.

Sigma Rule

title: Volmarg PMS Absolute Path Read via get-file Endpoint
id: 8f4a5d2e-1b3c-4a5d-9e8f-0a1b2c3d4e5f
status: experimental
description: Detects authenticated GET requests to /public/get-file/ with absolute filesystem paths, indicating potential CVE-2026-40526 exploitation.
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-40526
author: ValtersIT Threat Intelligence
date: 2026/01/15
logsource:
    category: webserver
    product: apache
    definition: 'Web server access logs or reverse proxy logs (nginx, HAProxy)'
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains|all:
            - '/public/get-file/'
    filter_benign:
        cs-uri-query|contains:
            - '/public/get-file/uploads/'      # Adjust to the legitimate base directory
            - '/public/get-file/documents/'
    condition: selection and not filter_benign
fields:
    - c-ip
    - cs-username
    - cs-uri-query
    - sc-status
falsepositives:
    - Legitimate file downloads from the allowed base directory if filter list is incomplete
level: high

YARA Rule

rule CVE_2026_40526_Volmarg_AbsolutePathRead
{
    meta:
        author = "ValtersIT Threat Intelligence"
        description = "Detects HTTP requests probing the Volmarg PMS get-file endpoint with absolute paths"
        date = "2026-01-15"
        cve = "CVE-2026-40526"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-40526"
        severity = "high"
    strings:
        $endpoint = "/public/get-file/"
        $abs_unix = /\/public\/get-file\/(\/etc\/|\/var\/|\/home\/|\/proc\/|\/root\/|\/usr\/|\/opt\/|\/srv\/|\/tmp\/)/
        $abs_win = /\/(public\/get-file\/)([A-Za-z]:\\|\/\/)/
        $traversal_alt = "/public/get-file/.."
    condition:
        uint16(0) == 0x4745 and  // "GET" method signature
        any of them
}

Suricata IDS Rule

alert http any any -> any any (
    msg:"CVE-2026-40526 - Volmarg PMS Absolute Path File Read Attempt";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/public/get-file/";
    pcre:"/\/public\/get-file\/(\/etc\/|\/var\/|\/home\/|\/proc\/|\/root\/|\/usr\/|\/opt\/|\/srv\/|\/tmp\/|\/boot\/|\/dev\/)/Ui";
    classtype:attempted-admin;
    sid:10040526;
    rev:1;
    reference:cve,2026-40526;
    metadata:created_at 2026-01-15, updated_at 2026-01-15;
)

Elastic Detection

sequence by source.ip
  [network where destination.port == 80 and http.request.method == "GET" and
   wildcard(http.request.uri, "*/public/get-file/*") and
   regex(http.request.uri, "/public/get-file/(/etc/|/var/|/home/|/proc/|/root/|/usr/|/opt/|/srv/|/tmp/)", "caseless") ]
  [file where event.action == "open" and process.name == "php-fpm*" and
   file.path == "/etc/passwd" or file.path == "/etc/shadow" or
   file.path startswith "/var/www/" ]

Splunk SPL Query

index=web sourcetype=access_combined
| where like(uri_path, "/public/get-file/%")
| regex uri_path="(?i)/public/get-file/(/etc/|/var/|/home/|/proc/|/root/|/usr/|/opt/|/srv/|/tmp/)"
| rex field=uri_path "/(?<recursive>.*)$"
| stats count by src_ip, uri_path, status, user
| sort - count
| rename src_ip as "Source IP", uri_path as "Requested Path", status as "HTTP Status", user as "Authenticated User"

Wazuh OSSEC Rule

<group name="web,volmarg,pci_dss_6.5.1,">
  <rule id="100526" level="10">
    <decoded>apache-accesslog</decoded>
    <match>/public/get-file/</match>
    <regex>(/etc/|/var/|/home/|/proc/|/root/|/usr/|/opt/|/srv/|/tmp/)</regex>
    <description>Volmarg PMS (CVE-2026-40526) absolute path file read attempt detected</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack_exploitation,</group>
    <info type="cve">CVE-2026-40526</info>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED

No patch, vendor advisory, or fix has been identified from any tracked source. The vendor (Volmarg) has not released a patched version, and no third-party patches or workarounds have been published. All deployments are considered vulnerable.

1. Immediate Mitigations (Compensating Controls)

Since no vendor patch exists, organizations must implement compensating controls:

2. Patch / Upgrade Steps

• Monitor vendor channels (Volmarg's GitHub repository, official website, and any security mailing lists) for a patched release.
• Until a patch exists, apply the input-validation middleware described above as a code-level workaround.
• If you have the ability to modify the application code directly, add the following logic before the file_get_contents() call:
  1. Use realpath() on the user-supplied path.
  2. Stack trace: verify the canonical path starts with the configured base directory.
  3. Reject the request if validation fails.

3. Long-Term Hardening

• Principle of Least Privilege: Ensure the PHP-FPM worker process runs with the minimum permissions required. It should only be able to read files within the application's data directories.
• Network Segmentation: Place the application behind a reverse proxy and restrict direct access to the PHP-FPM worker.
• File Permissions Auditing: Regularly audit file system permissions to ensure configuration files (.env, config.php) are not world-readable by the web user.
• Secrets Management: Move sensitive configuration (database passwords, API keys) to environment variables or a dedicated secrets manager, not hardcoded files that could be read.
• Authentication Hardening: Enforce strong passwords, MFA, and rate limiting on login to reduce the likelihood of attackers obtaining the low-privilege credentials required to exploit this flaw.
• Logging & Monitoring: Deploy the detection rules above and alert on any absolute-path requests to the vulnerable endpoint.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-40526
2. Volmarg Personal Management System (official site): https://volmarg.github.io/ — Monitor for future security advisories.
3. CWE-22 — Path Traversal (MITRE): https://cwe.mitre.org/data/definitions/22.html
4. CVSS v3.1 Calculator (FIRST): https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — CVE-2026-40526 is NOT currently listed; monitor for updates.

Vulnerability Status Summary:

Threat Actor Activity: No known threat actor campaigns or exploit-in-the-wild evidence have been associated with this CVE at the time of writing. However, given the low exploitation complexity and high confidentiality impact, this vulnerability is a prime candidate for inclusion in automated scanning toolkits and botnet operations. Organizations running this software should treat this as a priority-one remediation item despite the absence of active exploitation.