CVE-2026-111148 in libsidplayfp
Summary
by MITRE • 10/15/2026
libsidplayfp through 3.1.1 contains a heap out-of-bounds read vulnerability that allows attackers to crash applications by supplying a PSID/RSID file with an unchecked data offset. Attackers can set the header data offset beyond the file size, wrapping the length calculation so resolveAddrs() reads up to 64 KiB past the heap buffer.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in libsidplayfp versions through 3.1.1 represents a critical memory safety flaw classified as an out-of-bounds read within the context of C/C++ application development. This specific issue stems from insufficient validation of input data offsets when processing PSID and RSID file formats, which are standard audio container formats used to store sound data for Commodore 64 SID chips. The core technical failure lies in the resolveAddrs function, where the software fails to verify that a specified header data offset is within the bounds of the allocated heap buffer before proceeding with memory access operations. This lack of boundary checking allows an attacker to manipulate file metadata such that the calculated read location extends beyond the legitimate end of the buffer.
From a technical perspective, this flaw enables what is known as a heap-based out-of-bounds read vulnerability. When an attacker supplies a maliciously crafted PSID or RSID file with a header data offset set to exceed the actual file size, the application attempts to resolve memory addresses based on this invalid parameter. The length calculation logic in the vulnerable code path wraps around due to integer arithmetic issues or lack of saturation checks, resulting in a request to read up to 64 KiB past the end of the heap buffer. This behavior is characteristic of CWE-125, which describes out-of-bounds read vulnerabilities where software reads data beyond allocated memory boundaries. The magnitude of the over-read, potentially reaching 64 KiB, significantly increases the likelihood of accessing sensitive information or triggering system instability depending on what lies adjacent to the heap allocation in memory.
The operational impact of this vulnerability is primarily centered around application stability and availability rather than direct code execution. Because the flaw involves reading data rather than writing to it, the immediate consequence is typically a segmentation fault or access violation that causes the host application to crash. This denial of service condition can be triggered remotely if the library is integrated into an application that processes untrusted audio files from network sources or user uploads. While out-of-bounds reads are generally less severe than writes because they do not directly allow arbitrary code execution, they remain dangerous as they may leak sensitive memory contents to the attacker through side channels or error messages, potentially aiding in further exploitation attempts against the host system.
In terms of threat modeling and industry standards, this vulnerability aligns with MITRE ATT&CK techniques related to Discovery, specifically T1083 File and Directory Discovery if used for information gathering, though its primary classification remains under Impact due to the denial of service potential. It also reflects common pitfalls in legacy audio processing libraries where performance optimizations often bypass rigorous input validation. The vulnerability underscores the importance of strict boundary checks when parsing binary file formats that contain variable-length headers or offset tables. Developers integrating libsidplayfp must recognize that even seemingly benign media files can serve as vectors for crashing services if proper sanitization is not applied at ingestion points.
Mitigation strategies should focus on immediate patching and defensive coding practices. The most effective remediation is to upgrade the library to a version later than 3.1.1 where this offset validation has been corrected. For applications that cannot immediately update, developers must implement explicit bounds checking before calling resolveAddrs or any function that processes file offsets. This includes verifying that the declared data offset plus the expected length does not exceed the total buffer size allocated for the file content. Additionally, implementing fuzzing tests on audio input pipelines can help identify similar edge cases in other parsing logic within the codebase. Security teams should also consider deploying runtime application self-protection mechanisms or memory safety wrappers if upgrading is not immediately feasible to detect and terminate processes exhibiting abnormal memory access patterns.