CVE-2026-74973 in Firefox
Summary
by MITRE • 08/18/2026
Race condition, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/19/2026
The identified security flaw resides within the graphics subsystem of Mozilla Firefox, specifically involving a race condition coupled with a use-after-free vulnerability. This combination represents a critical class of memory safety issues that can lead to arbitrary code execution under specific conditions. The root cause typically involves multiple threads or processes accessing shared graphical resources without proper synchronization mechanisms, allowing an attacker to manipulate the timing of operations such that a pointer is used after its underlying memory has been deallocated and potentially reallocated for different purposes. In the context of browser graphics processing, this often relates to how image data, canvas elements, or WebGL contexts are managed during rendering pipelines where asynchronous updates occur concurrently with garbage collection or resource cleanup routines.
From a technical perspective, race conditions in multi-threaded environments create non-deterministic behavior that is difficult to reproduce and exploit consistently without precise timing control. When combined with use-after-free errors, the vulnerability allows an attacker who can trigger specific graphical operations through malicious web content to gain access to freed memory regions. If the browser reallocates this memory for a different object type before the stale pointer is dereferenced, it results in type confusion or arbitrary read/write capabilities within the process space of the renderer. This capability effectively bypasses standard sandboxing protections because the attacker gains control over memory layout and execution flow at a low level, potentially leading to full system compromise if additional exploitation steps are chained successfully against other browser components or operating system defenses.
The operational impact of this vulnerability is severe due to its potential for remote code execution via crafted web pages. An attacker could host a specially designed webpage containing malicious JavaScript that triggers the specific sequence of graphics operations required to exploit the race condition and use-after-free state. Successful exploitation would allow the attacker to execute arbitrary commands on the victim's machine with the privileges of the browser process, which may have access to local files, network resources, or other sensitive data depending on user permissions and configured security policies. This risk is particularly acute for users who frequently visit untrusted websites or are targeted by sophisticated phishing campaigns that leverage advanced persistent threat techniques involving memory corruption exploits.
Mitigation strategies primarily rely on the timely application of vendor-provided patches to ensure all instances of Firefox are updated to versions where this flaw has been remediated, specifically version 154 for standard releases and ESR branches 115.39, 140.14, and 153.1. Organizations should enforce automated update policies to minimize the window of exposure across all endpoints running Firefox browsers. Additionally, enabling strict content security policies and disabling unnecessary JavaScript features can reduce the attack surface available to potential exploiters. Security teams should also monitor for indicators of compromise related to memory corruption attempts in browser logs and consider deploying endpoint detection and response solutions capable of identifying anomalous behavior patterns associated with heap spraying or type confusion attacks commonly used in conjunction with such vulnerabilities.
This vulnerability aligns with Common Weakness Enumeration identifiers CWE-362 for race conditions involving shared resources without proper synchronization, and CWE-416 for use-after-free errors where pointers are not invalidated after memory release. In terms of the MITRE ATT&CK framework, this flaw facilitates techniques related to Initial Access through exploit public applications or Defense Evasion via process injection if the attacker leverages the arbitrary write capability to inject code into legitimate processes. Understanding these mappings helps in prioritizing remediation efforts and enhancing detection rules within security information and event management systems to better identify attempts to leverage similar memory safety flaws in other software components.