CVE-2026-21822 in AppScan
Summary
by MITRE • 09/18/2026
HCLSoftware AppScan 360° was affected by a Path Traversal vulnerability in the ASReportService component. Improper handling of file paths allows an authenticated attacker to read or write files outside the intended directory, potentially enabling file system structure inspection or unauthorized file modification within the application's directory scope.
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Analysis
by VulDB Data Team • 09/18/2026
The HCL Software AppScan 360° platform contains a critical path traversal vulnerability located specifically within its ASReportService component. This flaw stems from an improper validation and sanitization of user-supplied input that constructs file system paths. In secure software design, applications must strictly enforce directory boundaries to ensure that operations such as reading or writing files are confined to the intended application directories. However, in this instance, the service fails to adequately neutralize special elements within the path specification, specifically sequences like dot-dot-slash (..). This oversight allows an attacker to manipulate file paths to escape the restricted context and access arbitrary locations on the underlying operating system's file structure.
The technical nature of this vulnerability aligns with Common Weakness Enumeration identifier CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The root cause lies in the application logic which trusts user input without sufficient verification against directory traversal patterns. When an authenticated attacker interacts with the ASReportService, they can inject these malicious path sequences into parameters that dictate file operations. By doing so, the server resolves the path relative to the current working directory rather than restricting it to a predefined safe zone. This mechanism effectively bypasses access controls designed to isolate application data from sensitive system files or other user data stored on the same filesystem.
The operational impact of this vulnerability is significant due to its potential for both information disclosure and unauthorized modification. An authenticated attacker can exploit this flaw to read critical configuration files, source code, database credentials, or internal logs that reside outside the intended directory scope. This capability facilitates deep reconnaissance of the application's architecture and infrastructure. Furthermore, if write permissions are granted in certain contexts within the ASReportService component, an attacker could overwrite existing files with malicious content. Such actions could lead to service disruption through file corruption or potentially serve as a precursor for further attacks such as remote code execution if specific executable files can be overwritten or manipulated.
This vulnerability is also relevant to MITRE ATT&CK techniques related to Collection and Exfiltration, specifically those involving local data staging or indirect command execution via file system manipulation. The ability to traverse directories allows an attacker to map out the server environment, identifying high-value targets for subsequent exploitation phases. It undermines the principle of least privilege by granting access beyond what is necessary for normal application function once authentication has been achieved.
Mitigation strategies must focus on both immediate remediation and long-term secure coding practices. The primary fix involves updating HCL Software AppScan 360° to a version where this vulnerability has been patched, ensuring that the ASReportService properly validates all file path inputs. Developers should implement strict allow-listing for permitted characters in filenames and directories rather than relying on block lists which may miss novel traversal sequences. Additionally, employing canonicalization techniques before processing paths can help detect attempts to escape directory boundaries by resolving symbolic links and relative references into their absolute forms. Access controls should be reinforced at the operating system level using chroot jails or containerized environments to limit the blast radius of any successful exploitation attempt. Regular security audits and static code analysis focused on file I/O operations are recommended to prevent similar weaknesses in future development cycles.