CVE-2026-64949 in Pandora FMS
Summary
by MITRE • 10/01/2026
Incomplete extension blacklist in the File Manager module allows authenticated upload and execution of arbitrary .phar files. Affects Pandora FMS from 777 onwards.
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified as an incomplete extension blacklist within the File Manager module of Pandora FMS represents a critical security flaw that undermines the integrity of file uploads in enterprise monitoring environments. This issue specifically affects versions starting from build 777 and allows authenticated users to bypass intended restrictions on file types. The core technical failure lies in the application's logic for validating uploaded files, where the blacklist mechanism is insufficiently comprehensive or improperly implemented. Instead of relying solely on a restrictive allow-list approach which would be more secure, the system depends on excluding known malicious extensions while permitting others. This architectural decision creates an attack surface wherein attackers can exploit gaps in the filtering logic to upload and subsequently execute arbitrary PHP Archive (PHAR) files.
From a technical perspective, PHAR files are serialized PHP objects that, when instantiated by the application, trigger their own constructors or destructors. If these objects contain malicious payloads such as Remote Code Execution (RCE) vectors, they can be executed automatically upon deserialization. The vulnerability arises because the File Manager module fails to adequately sanitize or validate the content of uploaded files beyond simple extension checking. An authenticated attacker who has access to this module can craft a PHAR file containing serialized objects with malicious payloads and upload it through the interface. Because the blacklist is incomplete, the system accepts the .phar extension as valid, leading to its storage on the server. Subsequent actions that trigger deserialization of these files result in arbitrary code execution under the context of the web service user account.
The operational impact of this vulnerability is severe, particularly given that it requires authentication rather than being remotely exploitable without credentials. However, authenticated access can be obtained through various means including credential stuffing, phishing, or exploitation of other lower-severity vulnerabilities within the same application ecosystem. Once an attacker gains valid login credentials and accesses the File Manager module, they can achieve full remote code execution on the underlying server infrastructure. This compromises not only the Pandora FMS instance itself but potentially any systems accessible from that network segment due to lateral movement opportunities. The ability to execute arbitrary commands means attackers could exfiltrate sensitive monitoring data, modify configurations to hide their presence, or use the compromised host as a pivot point for further attacks against critical assets monitored by the platform.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-434, which describes the Unrestricted Upload of File with Dangerous Type. It also relates closely to CWE-20 Improper Input Validation and CWE-915 PHP Object Injection when considering the mechanism of exploitation via PHAR deserialization. In terms of the MITRE ATT&CK framework, this flaw facilitates Initial Access through valid accounts if credentials are compromised, followed by Execution techniques such as Command Line Interface or Scripting Interpreter abuse depending on how the PHAR payload is triggered. The persistence aspect may also be relevant if attackers modify system configurations to maintain access after exploitation.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary recommendation is to apply vendor-provided patches immediately for all affected versions of Pandora FMS starting from build 777. Organizations should verify their current version against the latest release notes provided by the vendor to ensure they are running a patched iteration where this blacklist logic has been corrected or replaced with stricter validation methods. In addition to patching, administrators should enforce strict file upload policies that utilize allow-lists rather than deny-lists for permitted extensions. Implementing Web Application Firewall rules can provide an additional layer of defense by inspecting uploaded files and blocking attempts to upload PHAR archives regardless of the application's internal logic.
Furthermore, principle of least privilege should be applied strictly to user accounts with access to file management modules. Regular audits of user permissions ensure that only necessary personnel have elevated privileges within the File Manager interface. Enabling multi-factor authentication reduces the risk of credential compromise leading to exploitation of this vulnerability. Monitoring logs for unusual upload patterns or unexpected process executions stemming from web service accounts can aid in early detection of attempted exploits. Finally, conducting regular penetration tests focused on file upload functionality and deserialization vulnerabilities helps identify similar weaknesses before they are exploited by malicious actors.