CVE-2017-8817 in macOS
Summary
by MITRE
The FTP wildcard function in curl and libcurl before 7.57.0 allows remote attackers to cause a denial of service (out-of-bounds read and application crash) or possibly have unspecified other impact via a string that ends with an '[' character.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability identified as CVE-2017-8817 resides within the File Transfer Protocol wildcard handling functionality of curl and libcurl software versions prior to 7.57.0. This flaw represents a critical security issue that affects the core parsing mechanisms used for FTP directory listings and file name matching operations. The vulnerability specifically targets the processing of strings that terminate with an opening square bracket character, creating a dangerous condition in the software's internal buffer management and string parsing routines.
The technical implementation of this vulnerability stems from inadequate bounds checking within the FTP wildcard expansion code. When curl or libcurl encounters a string ending with a '[' character during FTP operations, the parsing logic fails to properly validate the string boundaries before attempting to access memory locations. This leads to out-of-bounds read operations that can cause the application to crash or potentially allow attackers to execute arbitrary code. The flaw operates at the level of memory management and string processing, making it particularly dangerous as it can be triggered through normal FTP protocol interactions without requiring special privileges or complex attack vectors.
From an operational impact perspective, this vulnerability creates significant risk for systems relying on curl or libcurl for FTP operations, particularly in environments where external network access is permitted. Attackers can craft malicious FTP responses or manipulate server configurations to trigger the out-of-bounds read condition, resulting in denial of service for legitimate users. The potential for unspecified other impacts suggests that under certain conditions, this vulnerability might enable more sophisticated attacks beyond simple service disruption, potentially allowing for privilege escalation or information disclosure scenarios. Organizations using affected versions of curl or libcurl in production environments face substantial risk of service interruption and potential compromise.
The vulnerability aligns with CWE-129, which describes improper validation of length of input buffers, and relates to ATT&CK technique T1210 for exploitation of remote services through malformed input processing. Security practitioners should prioritize immediate patching of all systems running vulnerable versions of curl or libcurl to address this issue. Organizations should also implement network segmentation and monitoring to detect potential exploitation attempts. The fix implemented in version 7.57.0 includes enhanced bounds checking and proper string validation routines that prevent the out-of-bounds memory access conditions. Regular security assessments and vulnerability management processes should include verification of curl and libcurl installations to ensure compliance with security best practices and prevent exploitation of similar buffer overflow conditions in other components of the software stack.