CVE-2026-81625 in Greenbone
Summary
by MITRE • 08/27/2026
A remote attacker with user privileges may use a malicious or compromised NASL vulnerability test (VT) on the affected products to trigger a stack buffer overflow and gain full access on the compromised system.
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Analysis
by VulDB Data Team • 08/27/2026
The described scenario highlights a critical security failure within network-based vulnerability assessment frameworks, specifically involving Network Vulnerability Tests or NASL scripts. This type of flaw represents a severe trust boundary violation where an attacker who has already obtained user-level privileges can escalate their access to full administrative control through a stack buffer overflow. The core technical mechanism involves the improper handling of input data by the vulnerable application component that processes these test scripts. When a maliciously crafted or compromised NASL script is executed, it supplies input data that exceeds the allocated size of the fixed-size buffer located on the call stack. This excess data overwrites adjacent memory locations, potentially corrupting critical control structures such as return addresses and saved frame pointers. By carefully crafting this overflow payload, an attacker can redirect program execution flow to inject and execute arbitrary machine code, thereby achieving remote code execution with the privileges of the process running the vulnerability scanner or agent.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) categories such as CWE-120 Buffer Copy without Checking Size of Input Classic Buffer Overflow and CWE-78 Improper Neutralization of Special Elements used in an OS Command if command injection is involved, though the primary vector here is memory corruption. From a tactical perspective, this exploit path maps to MITRE ATT&CK techniques including T1059 Command and Scripting Interpreter for executing the malicious script and potentially T1203 Exploitation for Client Execution or T1486 Data Encrypted for Impact if ransomware is deployed post-exploitation. The severity of this issue lies in its potential to compromise the integrity of vulnerability management systems, which are often central to an organization's security posture. If a scanner agent or server component is compromised via this method, it can lead to lateral movement across the network, as the attacker now possesses high-level access that may allow them to disable logging, exfiltrate sensitive data, or pivot to other critical infrastructure components.
The operational impact of such a vulnerability extends beyond immediate system compromise. It undermines the reliability of automated security assessments by allowing attackers to manipulate scan results or use the scanning infrastructure itself as a launchpad for further attacks. In environments where vulnerability scanners operate with elevated privileges to perform deep network probes, this flaw effectively neutralizes one of the primary defenses against external threats. Furthermore, if the NASL scripts are sourced from untrusted repositories or compromised third-party plugins, the attack surface expands significantly, enabling supply chain-style compromises within the security tooling itself.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Immediate actions should include applying vendor-provided patches that address the buffer overflow by implementing proper bounds checking for all inputs processed during NASL script execution. Organizations should also enforce strict code signing and integrity verification mechanisms for any custom or third-party vulnerability test scripts to prevent the deployment of maliciously modified files. In terms of defense in depth, deploying runtime application self-protection (RASP) solutions can detect anomalous memory access patterns indicative of buffer overflows before they result in full exploitation. Additionally, restricting the privileges under which vulnerability scanning agents operate is crucial; adhering to the principle of least privilege ensures that even if an overflow occurs, the resulting code execution does not grant root or administrator-level access. Regular auditing of script sources and maintaining a whitelist of approved plugins further reduces the risk associated with executing untrusted code within the assessment environment.