CVE-2022-28285 in Thunderbird
Summary
by MITRE • 12/22/2022
When generating the assembly code for <code>MLoadTypedArrayElementHole</code>, an incorrect AliasSet was used. In conjunction with another vulnerability this could have been used for an out of bounds memory read. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.
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Analysis
by VulDB Data Team • 05/17/2026
The vulnerability identified as CVE-2022-28285 represents a critical memory safety issue within the JavaScript engine of Mozilla Firefox and Thunderbird browsers. This flaw manifests during the generation of assembly code for the specific operation <code>MLoadTypedArrayElementHole</code>, which is part of the Just-In-Time compilation process used by the SpiderMonkey JavaScript engine. The core technical issue stems from the improper handling of AliasSet information during code generation, creating a scenario where memory access patterns become incorrectly optimized or analyzed by the compiler.
The vulnerability operates through a sophisticated exploitation chain that requires the combination of multiple flaws to achieve its full impact. When the incorrect AliasSet is used during assembly code generation for typed array element loading operations, it creates a mismatch in how the compiler tracks memory dependencies and aliases. This misalignment can result in the compiler making incorrect assumptions about memory access patterns, potentially allowing an attacker to manipulate the code generation process to access memory locations beyond the intended bounds.
The operational impact of this vulnerability extends across multiple browser versions and represents a significant threat to user security. Systems running Firefox versions prior to 99 or Firefox ESR versions prior to 91.8, as well as Thunderbird versions prior to 91.8, are all affected by this issue. The vulnerability's potential for enabling out-of-bounds memory reads creates opportunities for information disclosure, arbitrary code execution, and other serious security compromises that could be leveraged by malicious actors to gain unauthorized access to user systems.
From a security standards perspective, this vulnerability aligns with CWE-121 and CWE-125 categories, representing buffer overflow conditions and out-of-bounds reads respectively. The flaw also maps to ATT&CK techniques such as T1059.007 for JavaScript execution and T1068 for privilege escalation through memory corruption. The combination of these issues demonstrates how seemingly minor compiler optimization flaws can create significant security risks when exploited in conjunction with other vulnerabilities. The vulnerability's exploitation requires sophisticated knowledge of the JavaScript engine internals and memory management patterns, making it particularly dangerous as it can be used to bypass modern security mitigations such as ASLR and DEP.
Mitigation strategies for CVE-2022-28285 primarily focus on immediate version updates to patched browser releases. Organizations should prioritize upgrading to Firefox 99, Firefox ESR 91.8, or Thunderbird 91.8, which contain the necessary fixes for the AliasSet handling during code generation. Additionally, implementing network-level protections such as content security policies and sandboxing measures can help reduce the potential impact of exploitation attempts. Browser vendors have also recommended enabling additional security features like strict site isolation and enhanced memory protection mechanisms to further defend against potential exploitation scenarios.