CVE-2010-0734 in libcURL
Summary
by MITRE
content_encoding.c in libcurl 7.10.5 through 7.19.7, when zlib is enabled, does not properly restrict the amount of callback data sent to an application that requests automatic decompression, which might allow remote attackers to cause a denial of service (application crash) or have unspecified other impact by sending crafted compressed data to an application that relies on the intended data-length limit.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability described in CVE-2010-0734 affects libcurl versions between 7.10.5 and 7.19.7, specifically when the zlib compression library is enabled. This issue resides within the content_encoding.c file which handles automatic decompression of compressed content. The flaw represents a classic buffer over-read or memory corruption vulnerability that occurs during the decompression process when applications receive crafted compressed data. The vulnerability stems from insufficient validation of decompressed data length limits, creating a scenario where maliciously constructed compressed content can bypass normal data length constraints imposed by the application.
The technical implementation of this vulnerability exploits the automatic decompression feature in libcurl, which is designed to transparently handle compressed content from web servers. When zlib compression is enabled, libcurl automatically decompresses content before delivering it to the application. The flaw manifests when the decompression process does not properly enforce the expected data length limits that applications typically impose on received data. Attackers can craft compressed data that, when decompressed, exceeds the intended buffer boundaries or memory allocation limits, leading to memory corruption. This issue falls under CWE-129, which describes improper validation of length of input buffers, and specifically relates to improper restriction of operations within a recognized operating unit. The vulnerability can be categorized under ATT&CK technique T1203, which involves exploiting software vulnerabilities to cause system instability or crashes.
The operational impact of CVE-2010-0734 extends beyond simple denial of service to potentially allow more sophisticated attacks depending on the application environment. Applications using libcurl with automatic decompression enabled become vulnerable to remote code execution or privilege escalation if the memory corruption leads to exploitable conditions. The vulnerability affects any application that relies on libcurl for HTTP communication and uses automatic decompression of compressed content. This includes web browsers, HTTP clients, network monitoring tools, and any software that processes compressed web content. The specific nature of the vulnerability means that attackers can cause application crashes simply by sending specially crafted compressed data to vulnerable applications, making it particularly dangerous in server environments where applications might process untrusted content from multiple sources.
Mitigation strategies for this vulnerability require immediate patching of affected libcurl versions to the latest stable releases that contain the necessary fixes. Organizations should also implement network-level controls such as content filtering and decompression restrictions to prevent malicious compressed data from reaching vulnerable applications. Application developers should consider disabling automatic decompression when processing untrusted content and implement proper input validation and length checking mechanisms. Additionally, security monitoring should be enhanced to detect unusual patterns in decompression activities or memory usage that might indicate exploitation attempts. The fix typically involves implementing proper bounds checking during the decompression process and ensuring that decompressed data does not exceed predetermined size limits. System administrators should also conduct thorough vulnerability assessments to identify all applications that depend on vulnerable versions of libcurl and prioritize their remediation.