CVE-2026-92031 in Firefox
Summary
by MITRE • 09/15/2026
Information disclosure in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw resides within the ImageLib subsystem of Mozilla Firefox, a critical component responsible for decoding and rendering various image formats such as JPEG, PNG, GIF, and WebP. This vulnerability is classified under CWE-200, which denotes an Information Exposure through improper handling of sensitive data during processing operations. The root cause typically involves insufficient validation or sanitization of input parameters passed to the graphics library functions. When a specially crafted or malformed image file is processed by ImageLib, it may trigger unintended memory access patterns that allow an attacker to read portions of the application's memory space beyond the intended buffer boundaries. This type of flaw often stems from off-by-one errors, missing bounds checks, or improper handling of edge cases in complex decoding algorithms where internal state variables are not correctly reset or validated before being exposed through subsequent operations.
From a technical perspective, this information disclosure vulnerability allows for potential side-channel attacks or direct memory scraping depending on the specific implementation details and the version of the browser involved. An attacker could craft a malicious webpage containing an image with carefully constructed headers or pixel data that exploits these weaknesses in ImageLib. Upon rendering, the flaw may cause the browser to leak internal structures, such as pointers, cryptographic keys stored temporarily during decryption processes, or other sensitive context information associated with the current browsing session. This leakage can occur through timing differences, error messages returned by the graphics driver, or via memory corruption techniques that inadvertently expose adjacent heap data. The severity of this issue is heightened because it does not require user interaction beyond visiting a malicious site, making it suitable for drive-by download scenarios where no explicit click-through actions are necessary to trigger the exploit chain.
The operational impact of this vulnerability extends beyond simple data leakage. If an attacker successfully exploits this flaw, they may gain insights into the internal workings of the browser's rendering engine or access sensitive information from other tabs if same-origin policies are bypassed through related vulnerabilities in conjunction with this memory leak. This can facilitate further attacks such as cross-site scripting amplification, session hijacking, or credential theft by exposing authentication tokens stored in memory. Furthermore, consistent exposure to such flaws erodes the security boundary between untrusted web content and privileged browser processes, potentially leading to remote code execution if combined with other exploitation techniques like heap spraying or arbitrary write primitives derived from the leaked information.
To mitigate this risk, users must ensure that their browsers are updated to Firefox version 156, Firefox Extended Support Release (ESR) version 140.16, or ESR version 153.3, as these releases contain the necessary patches for ImageLib. These updates include rigorous input validation checks and enhanced memory safety features designed to prevent out-of-bounds reads during image decoding. Organizations should enforce automated patch management policies to ensure rapid deployment of security fixes across all endpoints running Firefox. Additionally, deploying content security policies that restrict the loading of external resources can reduce the attack surface by limiting exposure to untrusted images from third-party domains. Security teams should also monitor for indicators of compromise related to unusual memory usage patterns or unexpected network activity originating from browser processes, which may signal active exploitation attempts targeting this specific vulnerability class aligned with MITRE ATT&CK technique T1005, Data from Local System.