CVE-2018-6951 in Patch
Summary
by MITRE
An issue was discovered in GNU patch through 2.7.6. There is a segmentation fault, associated with a NULL pointer dereference, leading to a denial of service in the intuit_diff_type function in pch.c, aka a "mangled rename" issue.
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Analysis
by VulDB Data Team • 02/06/2023
The vulnerability identified as CVE-2018-6951 represents a critical denial of service flaw within GNU patch version 2.7.6 and earlier. This issue manifests as a segmentation fault caused by a NULL pointer dereference in the intuit_diff_type function located within the pch.c source file. The flaw specifically occurs during the processing of mangled rename operations, which are part of the patch application process used to modify source code files. The segmentation fault results in an abrupt program termination, effectively denying service to legitimate users attempting to apply patches to their code repositories.
The technical implementation of this vulnerability stems from inadequate input validation within the patch processing pipeline. When GNU patch encounters malformed or specially crafted patch files containing mangled rename sequences, the intuit_diff_type function fails to properly handle NULL pointer references during its internal processing. This function is responsible for determining the type of diff operation being performed, and under certain conditions involving corrupted or malicious patch data, it attempts to dereference a NULL pointer, causing the segmentation fault. The vulnerability is classified as a NULL pointer dereference under CWE-476, which represents a common class of software defects that can lead to system instability and denial of service conditions.
The operational impact of CVE-2018-6951 extends beyond simple program termination, as it can be exploited by attackers to disrupt patch management workflows across various software development environments. Systems relying on GNU patch for automated code updates, continuous integration pipelines, or software distribution mechanisms become vulnerable to service disruption when processing maliciously crafted patch files. This vulnerability particularly affects environments where patch validation is not performed before application, making it a significant concern for organizations that depend on automated patching processes. The flaw can be leveraged in scenarios involving untrusted patch sources, such as open source repositories, third-party software distributions, or collaborative development platforms where patch files may be submitted by unverified users.
Mitigation strategies for this vulnerability center on immediate software updates to GNU patch version 2.7.7 or later, which contains the necessary fixes to properly handle NULL pointer dereferences during mangled rename processing. Organizations should implement comprehensive patch management procedures that include validation of patch content before application, particularly for patches sourced from external repositories or untrusted environments. The implementation of input sanitization measures and enhanced error handling within patch processing workflows can provide additional defense layers. From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain unauthorized access or disrupt system operations. Regular security assessments and vulnerability scanning of development environments should include checks for outdated GNU patch installations to prevent exploitation of this and similar denial of service vulnerabilities that could compromise the integrity of software development processes and potentially enable more sophisticated attacks targeting the broader software supply chain.