CVE-2026-2783
Published: 24 February 2026
Description
Information disclosure due to JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Automated marking applies security attributes to system outputs, making it harder for attackers to exploit unmarked sensitive information leading to unauthorized exposure.
Proper attribute retention and permitted-value enforcement limits unauthorized actors from accessing sensitive information lacking correct labels.
Prevents unauthorized exposure of sensitive information by prohibiting untrusted external systems from processing or storing it.
By enforcing authorization matching prior to sharing, the control reduces the risk of exposing sensitive information to unauthorized actors.
Review and removal of nonpublic information from publicly accessible systems directly prevents exposure of sensitive data to unauthorized actors.
Data mining protection mechanisms detect and block unauthorized bulk extraction of sensitive data, directly mitigating exposure to unauthorized actors.
Literacy training teaches users to recognize and avoid actions that result in unauthorized exposure of sensitive information.
Retaining and monitoring training records confirms personnel have completed privacy and security awareness training on handling sensitive data, reducing the chance of unauthorized exposure due to lack of knowledge.
Security SummaryAI
CVE-2026-2783 is an information disclosure vulnerability stemming from JIT miscompilation in the JavaScript Engine's JIT component. It affects Mozilla Firefox versions prior to 148, Firefox ESR prior to 140.8, Thunderbird prior to 148, and Thunderbird prior to 140.8. The issue is classified under CWE-843 (Access of Resource Using Incompatible Type) and CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high severity due to its potential for confidential data exposure.
Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low complexity. Successful exploitation enables high-impact confidentiality violations, such as leaking sensitive memory contents from the JavaScript engine, potentially exposing user data, tokens, or other process information without affecting integrity or availability.
Mozilla's security advisories (MFSA 2026-13, 2026-15, 2026-16, and 2026-17) and Bugzilla entry 2010943 detail the fix applied in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8. Security practitioners should prioritize updating affected products to these versions or later to mitigate the risk.
Details
- CWE(s)
Affected Products
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Info disclosure via JS engine memory leak directly enables collection of process data/credentials from browser without needing file access or separate dumping techniques.