CVE-2015-4042 in Coreutils
Summary
by MITRE
Integer overflow in the keycompare_mb function in sort.c in sort in GNU Coreutils through 8.23 might allow attackers to cause a denial of service (application crash) or possibly have unspecified other impact via long strings.
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Analysis
by VulDB Data Team • 10/01/2025
The vulnerability identified as CVE-2015-4042 represents a critical integer overflow flaw within the GNU Coreutils sorting functionality, specifically in the keycompare_mb function located in sort.c. This issue affects versions of GNU Coreutils through 8.23 and demonstrates how seemingly benign sorting operations can become vectors for system instability. The vulnerability manifests when processing long strings during sorting operations, creating conditions where integer arithmetic operations exceed their maximum representable values, leading to unpredictable behavior in the application's memory management and control flow.
The technical exploitation of this vulnerability occurs within the keycompare_mb function which handles multibyte character comparisons during sorting processes. When the function processes extremely long strings, the integer variables used to track string lengths and positions can overflow, causing the application to behave erratically. This integer overflow condition can result in buffer overflows, memory corruption, or invalid memory access patterns that ultimately lead to application crashes. The flaw stems from inadequate input validation and overflow checking within the sorting algorithm's string handling mechanisms, making it particularly dangerous in environments where untrusted input is processed through the sort command.
The operational impact of CVE-2015-4042 extends beyond simple denial of service scenarios, as the vulnerability could potentially enable more sophisticated attacks depending on the execution environment. When exploited, the vulnerability can cause applications to crash or behave unpredictably, effectively creating a denial of service condition that disrupts legitimate system operations. In certain configurations or when combined with other vulnerabilities, the integer overflow could potentially be leveraged to execute arbitrary code, though the primary risk remains application instability and service disruption. The vulnerability affects systems that rely on GNU Coreutils for sorting operations, particularly those processing large datasets or user-provided input through the sort command.
Mitigation strategies for CVE-2015-4042 focus on both immediate patching and operational hardening measures. The most effective approach involves upgrading to GNU Coreutils version 8.24 or later, where the integer overflow vulnerability has been addressed through proper input validation and overflow checking mechanisms. System administrators should also implement input length restrictions when processing user data through sort operations, particularly in environments where untrusted input is common. Additionally, deploying intrusion detection systems that monitor for unusual sort command usage patterns and implementing proper access controls to limit who can execute sorting operations on sensitive systems can help reduce the attack surface. This vulnerability aligns with CWE-190, which describes integer overflow conditions, and represents a classic example of how improper input validation can lead to security issues, potentially mapping to ATT&CK technique T1499.004 for denial of service through resource exhaustion or application instability.