overview
CVE-2025-39551 is a critical deserialization vulnerability in FluentBoards, developed by Mahmudul Hasan Arif, which permits Object Injection via the unsafe deserialization of untrusted data. The flaw is assigned a CVSS score of 9.8 and an EPSS rating of 0.89, clearly indicating both high severity and a strong likelihood of exploitation.
POTENTIAL IMPACT
A successful attack enables remote injection of arbitrary objects into the application, leading to possible remote code execution, logic manipulation, or privilege escalation. This gravely threatens confidentiality, integrity, and availability of affected systems.
EXPLOITATION DETAILS
Attackers exploit this flaw by submitting specially crafted serialized data. Owing to insufficient input validation, the application deserializes attacker-controlled data, allowing object injection and the execution of arbitrary code or malicious actions—typically with no user interaction required.
AFFECTED PRODUCTS AND VERSIONS
- Software: FluentBoards (Mahmudul Hasan Arif)
- Vulnerable Versions: All releases through version 1.47 are affected.
- Patched/Mitigated Versions: As of now, there are no confirmed patched releases. Users should monitor vendor advisories and employ mitigation strategies, including input validation, disabling deserialization where possible, and considering virtual patching.
CURRENT THREAT STATUS
- There is no verified public evidence of active exploitation; however, given the high ratings and exploitability, attackers are expected to target unpatched systems soon if not already.
- The main attack technique involves sending malicious serialized payloads to endpoints that process deserialized data, targeting remote code execution or unauthorized alteration of application data.
- No specific industries or sectors are yet reported as targeted. Environments that expose the affected application to untrusted input remain at high risk.
INDICATORS OF COMPROMISE (IOCS)
At present, there are no publicly known Indicators of Compromise (IOCs) for successful exploitation of CVE-2025-39551 in FluentBoards. Avertium continuously monitors and investigates for any emerging IOCs. Should relevant IOCs—such as suspicious IPs, domains, file hashes, or malware signatures—emerge, they will be quickly disclosed to ensure timely guidance and customer protection.
RECOMMENDATIONS
- Monitor authoritative threat intelligence feeds (NIST NVD, CISA, vendor advisories) for updates.
- Organizations requiring support for detection or mitigation should contact their Avertium Service Delivery Manager or Account Executive.
MITRE ATT&CK ttPS
Deserialization vulnerabilities like CVE-2025-39551 commonly map to several MITRE ATT&CK tactics and techniques, as outlined below:
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Tactic
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Technique
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Technique ID
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Explanation
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Initial Access
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Exploit Public-Facing Application
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T1190
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Exploiting exposed FluentBoards instances to gain entry
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Execution
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Command and Scripting Interpreter
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T1059
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Running arbitrary commands post-deserialization
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Execution/Defense
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Process Injection
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T1055
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Injecting code into legitimate processes to evade detection
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Persistence
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Event Triggered Execution
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T1546
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Ensuring persistence via web shells or script modification
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Privilege Escalation
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Exploitation for Privilege Escalation
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T1068
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Gaining higher privileges via exploited service
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Impact
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Data Destruction
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T1485
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Destroying or modifying data with executed payloads
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Key Techniques in Context:
- T1190 – Exploit Public-Facing Application: Adversaries may target internet-exposed FluentBoards instances using crafted serialized objects to achieve arbitrary code execution.
- T1059 – Command and Scripting Interpreter: Post-exploitation, adversaries can execute arbitrary scripts or shell commands on the system.
- T1055 – Process Injection: Process injection may be used after deserialization to run attacker code in trusted processes, improving stealth and bypassing security controls.
- T1546 – Event Triggered Execution: Attackers could plant web shells or alter startup scripts, triggering malicious code on service events or restarts.
- T1068 – Exploitation for Privilege Escalation: Exploitation may permit escalation to system or admin privileges, particularly if the service operates with elevated rights.
- T1485 – Data Destruction: Malicious payloads could lead to data destruction or tampering, either as a direct action or via exploitation side effects.
additional Recommendations + information
CVE-2025-30391 carries a CVSS rating of 8.1, underscoring its significant risk. Organizations are urged to take the following mitigation and defense steps:
IMMEDIATE MITIGATION MEASURES
- Restrict or disable features in FluentBoards that process serialized input from users or untrusted sources.
- Limit user permissions, especially for accounts accessing deserialization components.
- Place all internet-facing FluentBoards instances behind a firewall or VPN to reduce public exposure.
- Review and temporarily disable application integrations or plugins that rely on object deserialization until a patch is available.
- Use application-level allow lists to restrict accepted classes in deserialization.
PATCH AND SYSTEM MONITORING
- No confirmed vendor patch exists yet; closely monitor official channels for updates.
- Enterprise customers (e.g., Red Hat) should request patch prioritization if relevant.
- Apply vendor patches immediately once released. - Implement monitoring to detect suspicious deserialization activity or unusual process access.
- Enable logging of all deserialization events, reviewing for anomalies.
- Set up alerts for uncharacteristic activity involving FluentBoards, especially file or network operations
NETWORK SECURITY ENHANCEMENTS
- Deploy IDS/IPS solutions to monitor for exploit attempts targeting deserialization flaws.
- Block known malicious IPs and restrict FluentBoards access to trusted networks.
- - Segment the environment hosting FluentBoards to limit lateral movement if compromised.
- Continuously update threat intelligence sources and block identified IOCs.
- Use web application firewalls (WAF) with rules tailored to deserialization attacks on FluentBoards.
If no patch is available, rely on compensating controls—disabling deserialization, improving input validation, and closely monitoring system/network activity. Remain alert for vendor advisories and apply remediations as soon as they are released.
ADDITIONAL SERVICE OFFERINGS
Avertium offers a range of services to help organizations address and defend against vulnerabilities like CVE-2025-39551:
Attack Surface Management (ASM)
- Comprehensive vulnerability identification across the IT environment, highlighting exposed instances of FluentBoards and similar risks.
- Prioritization of risk, blind spot analysis, and remediation guidance.
- Continuous monitoring for newly disclosed vulnerabilities and rapid assessment of potential impact.
Threat Detection & Response (TDR)
- Proactive monitoring and response to threats targeting deserialization vulnerabilities.
- Real-time detection of object injection, command execution, and persistence attempts.
- Integration with SIEM and XDR systems for unified, swift containment and remediation.
- Coverage extends to applications using FluentBoards or similar components.
Microsoft Security Solutions
- Security posture evaluation for Microsoft environments interacting with FluentBoards.
- Customized threat detection rules for deserialization and object injection.
- Data correlation across Microsoft tools to drive actionable alerts for suspicious activity.
- Endpoint management strategies to reduce risk from vulnerable third-party software.
Governance, Risk, and Compliance (GRC)
- Compliance audits ensuring robust controls for sensitive applications.
- Enterprise risk management aligned with industry best practices.
- Policy development for secure third-party software use and implementation.
- Guidance for secure software development and risk mitigation across the business.
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