CVE-2016-8568 in libgit2
Summary
by MITRE
The git_commit_message function in oid.c in libgit2 before 0.24.3 allows remote attackers to cause a denial of service (out-of-bounds read) via a cat-file command with a crafted object file.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-8568 represents a critical out-of-bounds read flaw within the libgit2 library version 0.24.2 and earlier. This issue specifically affects the git_commit_message function located in the oid.c file, which is a core component of the library responsible for handling git object identifiers and commit messages. The vulnerability arises when the library processes a cat-file command with a specially crafted object file, creating a scenario where memory access occurs beyond the bounds of allocated buffers. This type of flaw falls under the category of memory safety issues and is classified as CWE-125, which describes out-of-bounds read conditions that can lead to unpredictable behavior and system instability.
The technical execution of this vulnerability occurs through the manipulation of git object files that contain malformed commit message data. When libgit2 attempts to parse these crafted objects, the git_commit_message function fails to properly validate the boundaries of the commit message data, leading to an out-of-bounds memory read operation. This allows remote attackers to craft malicious git objects that, when processed by vulnerable versions of libgit2, trigger memory access violations that can result in program crashes or denial of service conditions. The impact is particularly severe because libgit2 is widely used across numerous applications and systems that handle git repositories, making this vulnerability exploitable in a broad range of environments including development tools, continuous integration systems, and git hosting platforms.
The operational impact of CVE-2016-8568 extends beyond simple denial of service, as it can potentially be leveraged to cause more serious system instability or even information disclosure in certain scenarios. Systems that rely on libgit2 for processing git data, such as git servers, IDE plugins, and automated build systems, become vulnerable to attacks that can disrupt normal operations. The vulnerability is particularly concerning in environments where untrusted git data is processed, as attackers can craft malicious commit objects that will cause the affected applications to crash or behave unpredictably. This aligns with ATT&CK technique T1499.004, which describes denial of service via resource exhaustion or memory corruption, and demonstrates how seemingly benign git operations can become attack vectors when libraries contain memory safety flaws.
The remediation for this vulnerability requires upgrading to libgit2 version 0.24.3 or later, where the out-of-bounds read issue has been addressed through proper bounds checking in the git_commit_message function. Additionally, system administrators and developers should implement proper input validation for all git object processing, particularly when handling untrusted data from external sources. The fix typically involves adding boundary checks before memory access operations and ensuring that commit message parsing routines validate the length and structure of incoming data before processing. Organizations using libgit2 should conduct vulnerability assessments to identify systems running affected versions and prioritize patching to prevent exploitation. This vulnerability highlights the importance of maintaining up-to-date security libraries and demonstrates how memory safety issues in core components can have widespread implications across the software ecosystem.