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Mozilla disclosed two high-severity privilege escalation vulnerabilities affecting Firefox versions earlier than 149, including CVE-2026-4722 in the IPC component and CVE-2026-4717 in the Netmonitor component. The Netmonitor flaw also affects Firefox ESR versions earlier than 140.9.0. Both issues were formally published with Mozilla advisories and Bugzilla references, marking coordinated vendor disclosure and public tracking.
NVD analysis rated both bugs as high impact to confidentiality, integrity, and availability. CVE-2026-4717 received a CVSS v3.1 vector of AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating network-exploitable privilege escalation without user interaction, while CVE-2026-4722 was assigned AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, requiring user interaction. Mozilla linked the disclosures to security advisories including MFSA-2026-20 and MFSA-2026-22, and organizations using Firefox or Firefox ESR should prioritize updates to supported fixed versions.
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6 events from the most recent confirmed update back to the earliest known activity.
Mozilla published CVE-2026-4723, a use-after-free flaw in the JavaScript Engine affecting Firefox versions earlier than 149.0, with references to a Bugzilla entry and MFSA-2026-20. NVD issued its initial analysis the same day, classifying it as CWE-416 and assigning a critical CVSS v3.1 vector indicating remote exploitation with high impact.
Mozilla recorded CVE-2026-4725, a use-after-free vulnerability in the Graphics: Canvas2D component that can lead to a sandbox escape, affecting Firefox versions earlier than 149. NVD published its initial analysis the same day, classifying it as CWE-416 and assigning a high-severity CVSS v3.1 vector.
Mozilla published CVE-2026-4715, an uninitialized memory flaw in the Graphics: Canvas2D component affecting Firefox versions earlier than 149.0 and Firefox ESR versions earlier than 140.9.0. NVD published its initial analysis the same day, assigning a high-severity CVSS v3.1 vector and classifying the issue as CWE-908.
On the same day as disclosure, NVD added its initial analysis for CVE-2026-4717 with a high-severity CVSS v3.1 score, while the CVE-2026-4722 record was updated to include a CVSS v3.1 vector indicating high impact. These updates formalized severity assessment for both Mozilla privilege escalation flaws.
Mozilla formally disclosed CVE-2026-4722, a privilege escalation vulnerability in the Firefox IPC component affecting versions earlier than 149. The record added references to a Mozilla Bugzilla entry and a Mozilla security advisory for tracking and remediation.
Mozilla published CVE-2026-4717, a privilege escalation flaw in the Netmonitor component affecting Firefox versions earlier than 149.0 and Firefox ESR versions earlier than 140.9.0. The disclosure included references to Bugzilla and Mozilla security advisories MFSA-2026-20 and MFSA-2026-22.
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Multiple critical vulnerabilities were identified in Mozilla Firefox and Firefox ESR, with the most severe enabling arbitrary code execution. Affected versions include Firefox prior to 146, Firefox ESR prior to 115.31, and Firefox ESR prior to 140.6. The vulnerabilities include use-after-free in WebRTC (`CVE-2025-14321`), sandbox escape in Graphics (`CVE-2025-14322`), privilege escalation in the DOM (`CVE-2025-14323`), JIT miscompilation in the JavaScript Engine (`CVE-2025-14324`, `CVE-2025-14325`), and multiple memory safety bugs. Exploitation could allow attackers to install programs, modify or delete data, or create new accounts with full user rights, depending on the privileges of the compromised user. There are currently no reports of these vulnerabilities being exploited in the wild. Security advisories from both the Canadian Centre for Cyber Security and the Multi-State Information Sharing and Analysis Center (MS-ISAC) urge users and administrators to apply the latest updates immediately to mitigate risk. The advisories highlight the importance of prompt patching, especially for large organizations and government entities, as the risk is assessed as high for these sectors. The updates address all known vulnerabilities, and users with fewer system privileges are less impacted than those with administrative rights.
Jun 29, 2026
Mozilla released security updates for **Firefox 154**, supported **Firefox ESR** branches, and **Thunderbird** to fix a broad set of vulnerabilities affecting desktop and mobile users. Government and vendor advisories said the updates address **3 critical** and **17 high-severity** flaws involving arbitrary code execution, privilege escalation, security restriction bypass, sandbox escape, site isolation failures, use-after-free conditions, and information disclosure. Firefox 154 also introduced product changes including expanded Local Access Network protections for WebSocket connections, while security notices from Canada and Italy urged organizations to review Mozilla bulletins and update affected installations. Tenable and downstream Linux advisories flagged the issue set as **critical** across Windows, macOS, and Slackware packages, with affected versions including Firefox releases prior to 154, multiple ESR builds before their patched versions, and Thunderbird releases prior to **140.14** or **154.0** depending on branch. Nessus coverage tied the fixes to numerous CVEs, including **`CVE-2026-74990`** as a scoring reference in several advisories, and highlighted specific Thunderbird issues such as a Remote Settings Client sandbox escape, a CanvasWebGL site isolation flaw, a DOM: Networking privilege escalation bug, and WebAssembly and garbage-collection use-after-free vulnerabilities. The recommended action across all notices was to upgrade Mozilla products to the latest patched versions immediately.
Aug 26, 2026
Mozilla released Firefox 146, addressing a series of high-impact security vulnerabilities, including several use-after-free flaws, privilege escalation issues, and a sandbox escape. Notable vulnerabilities include `CVE-2025-14321` (use-after-free in WebRTC: Signaling), `CVE-2025-14322` (sandbox escape in Graphics: CanvasWebGL), and multiple privilege escalation bugs in components such as DOM: Notifications and Netmonitor. Several JIT miscompilation vulnerabilities in the JavaScript Engine were also patched, along with a same-origin policy bypass and spoofing issue in the Downloads Panel. The update also resolves memory safety bugs affecting both Firefox and Thunderbird, some of which could potentially be exploited for remote code execution. Mozilla rates the overall impact of these vulnerabilities as high, urging users to update to Firefox 146 promptly to mitigate risk. The advisories provide CVE identifiers and reference associated bug reports for further technical details.
Jun 29, 2026