CVE-2020-8285 in Fujitsu M10-1, M10-4, M10-4S, M12-1, M12-2, M12-2S Servers
Summary
by MITRE • 12/15/2020
curl 7.21.0 to and including 7.73.0 is vulnerable to uncontrolled recursion due to a stack overflow issue in FTP wildcard match parsing.
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Analysis
by VulDB Data Team • 05/20/2025
The vulnerability identified as CVE-2020-8285 affects curl versions ranging from 7.21.0 through 7.73.0 and represents a critical stack overflow condition stemming from improper handling of FTP wildcard matching operations. This issue manifests when curl processes FTP URLs containing wildcard patterns, creating a scenario where recursive parsing operations can consume excessive stack memory without proper bounds checking. The flaw exists within the FTP wildcard matching implementation where the parser fails to adequately validate the depth of recursive calls during pattern expansion, leading to rapid stack exhaustion and potential application crash or arbitrary code execution.
The technical root cause of this vulnerability aligns with CWE-674, which describes uncontrolled recursion in software systems. When curl encounters an FTP URL with wildcard characters such as * or ?, the internal parsing routine recursively processes these patterns to match against available files on the remote server. The recursive algorithm does not implement proper recursion depth limits or stack usage monitoring, allowing maliciously crafted URLs to trigger unlimited recursive calls that consume stack space until the process terminates. This behavior constitutes a classic stack overflow vulnerability that can be exploited by attackers to either crash the application or potentially execute arbitrary code through controlled stack corruption.
The operational impact of CVE-2020-8285 extends beyond simple application instability to encompass potential system compromise and denial of service conditions. Attackers can craft malicious FTP URLs that trigger the recursive parsing behavior, leading to system crashes that can be leveraged for denial of service attacks against systems running vulnerable curl versions. In environments where curl is used for automated file transfers, web scraping, or integration with other applications, this vulnerability could enable attackers to disrupt critical services or potentially escalate privileges if the curl process runs with elevated permissions. The vulnerability affects both client-side applications that use curl for FTP operations and server-side systems that may process curl requests from untrusted sources.
Mitigation strategies for CVE-2020-8285 require immediate action to upgrade to curl version 7.74.0 or later, where the recursive parsing logic has been corrected to implement proper depth limits and stack usage monitoring. Organizations should conduct comprehensive inventory assessments to identify all systems running vulnerable curl versions and prioritize patching operations accordingly. Network administrators should implement URL filtering and validation mechanisms to prevent processing of suspicious FTP URLs containing wildcard patterns. The ATT&CK framework categorizes this vulnerability under T1210 - Exploitation of Remote Services and T1499 - Endpoint Denial of Service, indicating that exploitation requires targeting systems with vulnerable curl implementations and can result in service disruption or system compromise. Additional protective measures include implementing sandboxing for curl operations, monitoring for unusual memory consumption patterns, and establishing automated patch management processes to prevent future vulnerabilities of this nature from affecting the organization's infrastructure.