CVE-2018-5146 in Firefox
Summary
by MITRE
An out of bounds memory write while processing Vorbis audio data was reported through the Pwn2Own contest. This vulnerability affects Firefox < 59.0.1, Firefox ESR < 52.7.2, and Thunderbird < 52.7.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2018-5146 represents a critical out-of-bounds memory write flaw that emerged during the prestigious Pwn2Own security contest, highlighting the ongoing challenges in multimedia processing within web browsers. This issue specifically targets the Vorbis audio codec implementation within Mozilla's Firefox browser and Thunderbird email client, demonstrating how multimedia handling components can become attack vectors for sophisticated exploitation. The vulnerability's discovery through competitive security hacking underscores the importance of rigorous testing environments in identifying potential security gaps before they can be exploited in the wild.
The technical flaw manifests when the affected software processes Vorbis audio data, which is a popular open audio coding format commonly used in web applications and multimedia platforms. During normal operation, the software allocates memory buffers to handle audio frame data, but due to inadequate bounds checking in the Vorbis decoder implementation, maliciously crafted audio files can cause the program to write data beyond the allocated memory boundaries. This memory corruption vulnerability stems from improper validation of audio packet lengths and frame structures, allowing attackers to manipulate the decoder's memory management routines. The flaw operates at the intersection of multimedia processing and memory safety, making it particularly dangerous as it can be triggered through standard web browsing activities involving audio content.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential pathways for arbitrary code execution within the context of the affected applications. When an attacker successfully exploits this out-of-bounds write condition, they can manipulate memory contents to redirect program execution flow, potentially leading to full system compromise. The vulnerability affects multiple Mozilla products including Firefox browsers and Thunderbird email clients, making it particularly concerning for organizations that rely on these widely-used applications. The specific version ranges indicate that users running Firefox 59.0.1, Firefox ESR 52.7.2, and Thunderbird 52.7 or earlier versions remain vulnerable, emphasizing the need for prompt patch deployment across affected systems.
Security researchers categorize this vulnerability under CWE-787, which specifically addresses out-of-bounds write conditions, and it aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution. The vulnerability demonstrates how multimedia processing components often lack sufficient input validation, creating opportunities for attackers to leverage malformed data to achieve privilege escalation. Organizations should prioritize immediate patching of affected systems, as the vulnerability's exploitation potential makes it a high-priority concern for cybersecurity teams. The Pwn2Own disclosure also indicates that this vulnerability was likely already known to attackers, making proactive remediation essential. Additionally, network administrators should consider implementing content filtering measures to prevent potentially malicious audio files from reaching end-user systems, while security teams should monitor for any exploitation attempts targeting this specific memory corruption flaw.