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Mozilla patched multiple Firefox vulnerabilities, including a privacy flaw that let websites create hidden, stable identifiers without cookies by abusing the order of entries returned by IndexedDB. Researchers Dai Nguyen and Martin Bajanik of Fingerprint reported that the issue could persist across sessions and defeat protections expected from Firefox Private Browsing mode and Tor Browser’s New Identity feature, allowing sites to correlate activity that users believed was isolated.
Mozilla addressed the issue under Bug 2024220 in Firefox 150 and Firefox ESR 140.10.0, with additional fixes included in Firefox 150.0.3 and documented in Mozilla security advisories MFSA-2026-32 and MFSA-2026-45. The Tor Project also incorporated the fix in Tor Browser 15.0.10, while Germany’s dCERT later published Advisory 2026-1477 covering multiple Mozilla Firefox vulnerabilities.
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4 events from the most recent confirmed update back to the earliest known activity.
dCERT published Advisory 2026-1477 covering multiple vulnerabilities in Mozilla Firefox. The reference indicates downstream security notification of the Firefox vulnerability fixes.
Mozilla published advisory MFSA 2026-45 for Firefox 150.0.3, marking another release that addressed the privacy issue. TechRadar reports Mozilla patched the flaw in Firefox 150 and links it to Bug 2024220.
Dai Nguyen and Martin Bajanik of Fingerprint discovered a privacy flaw in Firefox and Tor Browser that let websites generate hidden, stable identifiers without cookies by exploiting the order of entries returned by IndexedDB. The issue enabled persistent fingerprinting across sessions, including Firefox Private Browsing mode and Tor Browser's New Identity mode.
Mozilla published advisory MFSA 2026-32 for Firefox ESR 140.10, indicating the vulnerability was fixed in ESR 140.10.0. TechRadar identifies this as the IndexedDB-based privacy flaw tracked under Bug 2024220.
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Researchers disclosed **CVE-2026-6770**, an IndexedDB information disclosure flaw in Firefox, Thunderbird, and Tor Browser that let websites derive a stable browser-process identifier without cookies. The issue came from the deterministic order returned by `indexedDB.databases()`, where internal UUID mappings and unsorted hash iteration exposed repeatable browser behavior that could be turned into a hidden fingerprint for cross-site tracking. The privacy impact was especially severe for users relying on anti-tracking features: the identifier could persist in **Firefox Private Browsing** and survive Tor Browser’s **New Identity** reset, allowing separate sites to correlate visits that users expected to be unlinkable. Mozilla said the bug was fixed in **Firefox 150**, **ESR 140.10**, and related Thunderbird releases, while the Tor Project patched it in **Tor Browser 15.0.10** by normalizing database ordering before exposure; no active exploitation was reported, but the flaw undermined core privacy guarantees in both products.
Jun 29, 2026
Mozilla released **Firefox 150** and updated **Firefox ESR** branches to address multiple security vulnerabilities, prompting downstream advisories from Debian and the Canadian Centre for Cyber Security. The fixes cover Firefox versions prior to `150`, Firefox ESR versions prior to `140.10` and `115.35`, and include vulnerabilities tracked as **CVE-2026-6768**, **CVE-2026-6784**, **CVE-2026-6785**, and **CVE-2026-6786**. **CVE-2026-6768** was described as a mitigation bypass in Firefox’s `Networking: Cookies` component and was assigned a **CVSS 9.8** score, indicating potentially severe impact if left unpatched. Mozilla also shipped related security fixes in **Thunderbird 150**, which uses Firefox’s web engine and addressed issues including a clickjacking and information disclosure flaw referenced in the Firefox advisories. Alongside the security patches, Mozilla’s releases included broad product updates such as privacy and platform changes in Firefox and improved encrypted-message search and OpenPGP features in Thunderbird. Government and Linux distribution advisories urged users and administrators to review Mozilla’s bulletins and apply the latest browser and mail client updates promptly.
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