CVE-2025-4082 in Thunderbird
Summary
by MITRE • 04/29/2025
Modification of specific WebGL shader attributes could trigger an out-of-bounds read, which, when chained with other vulnerabilities, could be used to escalate privileges. *This bug only affects Thunderbird for macOS. Other versions of Thunderbird are unaffected.*. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.
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Analysis
by VulDB Data Team • 04/15/2026
This vulnerability represents a critical out-of-bounds read condition within the WebGL rendering subsystem of Mozilla applications, specifically impacting Thunderbird versions on macOS platforms. The flaw manifests when specific WebGL shader attributes are modified, creating a memory access violation that extends beyond the intended boundaries of allocated memory regions. The vulnerability's exploitation potential is significantly amplified when combined with other security flaws, creating a pathway for privilege escalation attacks. The technical nature of this issue places it within the domain of memory safety vulnerabilities that are particularly dangerous in graphics rendering contexts where complex memory operations occur. This type of vulnerability falls under the CWE-125 category of out-of-bounds read conditions, which are commonly exploited in browser-based attacks due to the complex nature of WebGL operations and shader compilation processes.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides attackers with potential means to execute arbitrary code with elevated privileges. The fact that this affects only Thunderbird on macOS indicates a platform-specific code path or implementation difference that creates the vulnerability window. The exploitation chain likely involves leveraging the out-of-bounds read to gain information disclosure or memory corruption that can then be chained with additional primitives to achieve full privilege escalation. This vulnerability type aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers may use the privilege escalation to execute malicious code with system-level permissions. The attack surface is particularly concerning given that WebGL operations are frequently used in modern web applications and email clients for rich media content rendering.
Mozilla's patching strategy demonstrates the organization's approach to addressing browser security vulnerabilities through coordinated updates across their product line. The fix appears in multiple versions including the main Firefox release, extended support releases, and corresponding Thunderbird versions, indicating a comprehensive response to the vulnerability. This coordinated patching approach follows industry best practices for maintaining security across software ecosystems. The vulnerability's presence in Thunderbird but not other versions suggests that the macOS-specific implementation of WebGL rendering differs from other platforms, creating a unique attack vector. The remediation efforts likely involved memory bounds checking and validation of shader attribute modifications to prevent the out-of-bounds access condition. Security researchers should monitor for similar patterns in WebGL implementations across other browser vendors, as this vulnerability type represents a common attack surface in graphics rendering subsystems. The fix timeline shows that Mozilla responded promptly to the vulnerability, which is consistent with their established security update practices for critical issues.