CVE-2026-74945 in Firefox
Summary
by MITRE • 08/18/2026
Information disclosure in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/18/2026
The identified vulnerability resides within the text rendering subsystem of Mozilla Firefox's graphics architecture, specifically affecting how textual content is processed and displayed on screen. This component is responsible for converting Unicode strings into visual glyphs by interacting with system font libraries and rasterization engines. The flaw manifests as an information disclosure issue, which typically implies that sensitive data accessible to the application or operating system was inadvertently exposed through improper memory handling during text layout calculations. In complex web environments where dynamic content injection occurs frequently, such vulnerabilities can allow malicious scripts or crafted HTML structures to trigger unintended reads from adjacent memory regions or expose internal state variables that should remain encapsulated within the browser's security boundaries.
From a technical perspective, this defect likely stems from an improper validation of buffer bounds or a race condition during the asynchronous processing of text metrics and glyph positioning. When Firefox parses web content containing specific combinations of fonts, styles, or Unicode characters, it may fail to properly isolate temporary data structures used for layout calculations. This oversight can result in the leakage of heap memory contents that contain previously rendered information, internal pointers, or other sensitive artifacts from prior browsing sessions. Such behavior aligns with common patterns found in CWE-200, which categorizes vulnerabilities where an application exposes information to unauthorized actors through error messages, logs, or unintended data transmission during normal operation rather than explicit malicious exploitation of a logic flaw alone.
The operational impact of this vulnerability is primarily centered on the potential for side-channel attacks and context leakage within multi-tab browsing environments. An attacker hosting a malicious webpage could potentially exploit this weakness to infer information about other open tabs or internal browser states, thereby compromising user privacy and session integrity. While direct remote code execution is not indicated by the description of an information disclosure flaw, the exposure of memory layouts can facilitate further exploitation attempts by providing attackers with valuable data for crafting more precise attacks against other components of the browser engine. This represents a significant risk to users who engage in sensitive activities such as online banking or accessing confidential corporate resources via Firefox, as it undermines the fundamental isolation guarantees provided by modern web browsers.
Mitigation strategies focus on applying the vendor-provided patches that address these memory handling deficiencies within the text rendering pipeline. Users must update their installations of Mozilla Firefox and its Extended Support Release (ESR) branches to versions 154, ESR 115.39, ESR 140.14, or ESR 153.1 respectively, as these releases contain the necessary code corrections to enforce strict memory isolation during text processing operations. Additionally, security teams should ensure that browser auto-update mechanisms are enabled and functioning correctly to prevent exposure windows in enterprise environments where manual patching might be delayed. Monitoring for unusual network activity or unexpected behavior from Firefox processes can also serve as a secondary detection mechanism while patches are being deployed across systems.
This vulnerability is mapped to the MITRE ATT&CK framework under techniques related to Collection, specifically Data from Local System or potentially Screen Capture if visual artifacts were involved, though primarily it falls under Information Discovery phases where attackers gather system state information. It also correlates with CWE-200 as noted previously and may involve elements of CWE-125 Out-of-bounds Read depending on the specific memory access pattern identified during the fix process. By addressing these root causes through rigorous code review and enhanced fuzzing of text rendering inputs, Mozilla has reinforced the security posture of its browser engine against passive information leakage attacks that rely on subtle implementation flaws in core UI components.