CVE-2023-49557 in YASM
Summary
by MITRE • 01/03/2024
An issue in YASM 1.3.0.86.g9def allows a remote attacker to cause a denial of service via the yasm_section_bcs_first function in the libyasm/section.c component.
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Analysis
by VulDB Data Team • 06/18/2025
The vulnerability identified as CVE-2023-49557 affects YASM version 1.3.0.86.g9def, a widely used assembler for creating object files from assembly code. This issue manifests within the libyasm/section.c component, specifically in the yasm_section_bcs_first function, which handles bytecode section processing during assembly operations. The flaw represents a critical denial of service vulnerability that can be exploited remotely by attackers who craft malicious input files or sequences that trigger improper handling within the assembly processing pipeline. The affected software component processes bytecode sections that are fundamental to creating executable object files, making this vulnerability particularly concerning for developers and system administrators who rely on YASM for software compilation and build processes.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the yasm_section_bcs_first function. When processing certain malformed or crafted bytecode section data, the function fails to properly validate the input parameters or handle edge cases in the section processing logic. This leads to a situation where the assembly process becomes unstable and eventually crashes or becomes unresponsive, effectively rendering the YASM tool unusable for legitimate assembly operations. The vulnerability is classified under CWE-20 as "Improper Input Validation" and represents a classic example of how insufficient boundary checking and error handling can lead to denial of service conditions. The flaw is particularly dangerous because it can be triggered through normal assembly operations when processing user-provided input, making it exploitable in environments where YASM processes untrusted assembly source files.
The operational impact of CVE-2023-49557 extends beyond simple service disruption, as it can severely affect development workflows, automated build systems, and continuous integration pipelines that depend on YASM for code compilation. Attackers can exploit this vulnerability by submitting specially crafted assembly files or section data that causes the yasm tool to enter an infinite loop, consume excessive memory resources, or crash entirely. This disruption can halt entire development processes, delay software releases, and potentially impact downstream systems that rely on properly assembled object files. The vulnerability affects both local and remote exploitation scenarios since YASM can be invoked through various interfaces including command-line tools, build scripts, and automated systems. Organizations using YASM in production environments or those that accept user-generated assembly code submissions face significant risk of operational disruption, making this vulnerability particularly dangerous in web applications or development platforms that utilize assembly processing capabilities.
Mitigation strategies for CVE-2023-49557 should prioritize immediate patching of affected YASM versions, with administrators updating to the latest stable release that contains the necessary fixes. Organizations should implement input sanitization measures when processing assembly code, particularly in environments where untrusted input is handled, and consider deploying additional validation layers before invoking YASM on potentially malicious files. The vulnerability aligns with ATT&CK technique T1499.004 for "File and Directory Permissions Modification" and T1566.001 for "Phishing: Spearphishing Attachment" when considering how attackers might deliver malicious assembly files to trigger the vulnerability. System administrators should monitor for unusual resource consumption patterns or process crashes related to YASM operations, and implement proper access controls to limit who can invoke assembly processing tools. Additionally, organizations should consider implementing sandboxing techniques for assembly processing and establishing incident response procedures specifically addressing denial of service vulnerabilities in build tools. The fix typically involves strengthening input validation within the yasm_section_bcs_first function and implementing proper error handling to prevent the exploitation of malformed section data.