CVE-2023-45676 in stb_vorbis
Summary
by MITRE • 10/25/2023
stb_vorbis is a single file MIT licensed library for processing ogg vorbis files. A crafted file may trigger out of bounds write in `f->vendor[i] = get8_packet(f);`. The root cause is an integer overflow in `setup_malloc`. A sufficiently large value in the variable `sz` overflows with `sz+7` in and the negative value passes the maximum available memory buffer check. This issue may lead to code execution.
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Analysis
by VulDB Data Team • 04/21/2025
The stb_vorbis library represents a widely-used single-file implementation for processing ogg vorbis audio files, distributed under the permissive MIT license. This library serves as a critical component in numerous multimedia applications and systems where audio file parsing and decoding are required. The vulnerability under analysis stems from improper input validation within the library's parsing logic, specifically affecting the vendor string handling mechanism during file processing. The library's design relies on parsing structured data from ogg vorbis containers, where metadata including vendor strings are stored in a format that requires careful memory management and boundary checking. When processing maliciously crafted audio files, the library fails to properly validate the size parameters associated with memory allocation operations.
The technical flaw manifests through an integer overflow condition occurring within the setup_malloc function where the variable sz undergoes arithmetic operations that exceed the maximum representable value for the data type. The specific overflow occurs when sz+7 is computed, resulting in a negative value that bypasses the intended maximum buffer size validation checks. This vulnerability directly impacts the f->vendor[i] = get8_packet(f); operation where the out-of-bounds write occurs, allowing an attacker to write data beyond the allocated memory boundaries for the vendor string buffer. The root cause traces back to inadequate integer overflow protection in memory allocation calculations, where the library assumes that sz will always remain within valid bounds. This particular vulnerability aligns with CWE-190, which addresses integer overflow and underflow conditions, and represents a classic example of how improper integer handling can lead to memory corruption vulnerabilities. The issue demonstrates a fundamental flaw in the library's defensive programming practices where input validation is insufficient to prevent malicious data from causing memory corruption.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling remote code execution in systems that utilize stb_vorbis for audio processing. Attackers can craft malicious ogg vorbis files that, when processed by vulnerable applications, trigger the integer overflow condition and subsequent out-of-bounds write. This creates opportunities for arbitrary code execution, privilege escalation, or denial of service conditions depending on the target system's memory layout and protection mechanisms. The vulnerability affects any application or system that incorporates stb_vorbis and processes untrusted audio files, making it particularly dangerous in web applications, media processing systems, or any environment where user-uploaded content is parsed. The attack surface is broad given the library's widespread adoption across various platforms and applications, potentially affecting everything from desktop applications to web browsers and multimedia frameworks. The vulnerability's exploitability is enhanced by the fact that it requires no special privileges to trigger, making it particularly concerning for applications that process user-provided audio content.
Mitigation strategies for this vulnerability involve immediate patching of the stb_vorbis library to address the integer overflow condition in setup_malloc and implement proper bounds checking for memory allocation operations. Developers should ensure that sz+7 calculations are properly validated to prevent overflow conditions and that all memory allocation sizes are checked against maximum allowable limits. The fix should include explicit overflow detection before arithmetic operations and proper validation of input parameters that determine buffer sizes. Additionally, applications should implement robust input validation and sandboxing mechanisms when processing audio files, including limiting the maximum size of files that can be processed and implementing memory safety checks. Organizations should also consider implementing runtime protections such as address space layout randomization and stack canaries to reduce the effectiveness of potential exploitation attempts. The vulnerability highlights the importance of secure coding practices and proper integer overflow protection, particularly in libraries that handle untrusted input data. This issue serves as a reminder of the critical need for thorough input validation and defensive programming techniques, aligning with ATT&CK technique T1203 for process injection and T1059 for command and scripting interpreter, which may be relevant in exploitation scenarios involving memory corruption vulnerabilities.