CVE-2026-4718

Undefined behavior in the WebRTC: Signaling component

Undefined behavior in the WebRTC: Signaling component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Firefox Esr Thunderbird

CVE-2026-4720

Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149

Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Firefox Esr Thunderbird

CVE-2026-4729

Memory safety bugs fixed in Firefox 149 and Thunderbird 149

Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Thunderbird

CVE-2026-4721

Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149

Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Firefox Esr Thunderbird

CVE-2026-3889

Spoofing issue in Thunderbird

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Thunderbird

CVE-2026-4371

Out of bounds read in IMAP parsing

A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Thunderbird

CVE-2026-5732

Incorrect boundary conditions, integer overflow in the Graphics: Text component

Incorrect boundary conditions, integer overflow in the Graphics: Text component. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Firefox Esr Thunderbird

CVE-2026-5733

Incorrect boundary conditions in the Graphics: WebGPU component

Incorrect boundary conditions in the Graphics: WebGPU component. This vulnerability was fixed in Firefox 149.0.2 and Thunderbird 149.0.2.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Thunderbird

CVE-2026-5734

Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Firefox Esr Thunderbird

CVE-2026-5735

Memory safety bugs fixed in Firefox 149.0.2 and Thunderbird 149.0.2

Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2 and Thunderbird 149.0.2.

CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed

Vendors

Mozilla

Products

Firefox Thunderbird

CVE-2015-0797

Mozilla: Buffer overflow parsing H.264 video with Linux Gstreamer (MFSA 2015-47)

GStreamer before 1.4.5, as used in Mozilla Firefox before 38.0, Firefox ESR 31.x before 31.7, and Thunderbird before 31.7 on Linux, allows remote attackers to cause a denial of service (buffer over-read and application crash) or possibly execute arbitrary code via crafted H.264 video data in an m4v file.

CVSS 2.0 · 6.8 Medium EPSS 5.4% KEV · Not listed

Vendors

Debian Gstreamer Linux and 3 more

Products

Debian Linux Gstreamer Linux Kernel and 13 more

CVE-2024-9397

firefox: thunderbird: Potential directory upload bypass via clickjacking

A missing delay in directory upload UI could have made it possible for an attacker to trick a user into granting permission via clickjacking. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

CVSS 3.1 · 6.1 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 6 more

CVE-2024-5692

Mozilla: Bypass of file name restrictions during saving

On Windows 10, when using the 'Save As' functionality, an attacker could have tricked the browser into saving the file with a disallowed extension such as `.url` by including an invalid character in the extension. *Note:* This issue only affected Windows operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Microsoft Mozilla

Products

Windows Firefox Thunderbird

CVE-2023-4582

Buffer Overflow in WebGL glGetProgramiv

Due to large allocation checks in Angle for glsl shaders being too lenient a buffer overflow could have occurred when allocating too much private shader memory on mac OS. *This bug only affects Firefox on macOS. Other operating systems are unaffected.* This vulnerability affects Firefox < 117, Firefox ESR < 115.2, and Thunderbird < 115.2.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed

Vendors

Apple Mozilla

Products

Macos Firefox Firefox Esr and 1 more

CVE-2023-3600

Use-after-free in workers

During the worker lifecycle, a use-after-free condition could have occurred, which could have led to a potentially exploitable crash. This vulnerability affects Firefox < 115.0.2, Firefox ESR < 115.0.2, and Thunderbird < 115.0.1.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more

CVE-2023-23605

Memory safety bugs fixed in Firefox 109 and Firefox ESR 102.7

Mozilla developers and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 108 and Firefox ESR 102.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more

CVE-2023-23603

Calls to console.log allowed bypassing Content Security Policy via format directive

Regular expressions used to filter out forbidden properties and values from style directives in calls to `console.log` weren't accounting for external URLs. Data could then be potentially exfiltrated from the browser. This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more

CVE-2023-23602

Content Security Policy wasn't being correctly applied to WebSockets in WebWorkers

A mishandled security check when creating a WebSocket in a WebWorker caused the Content Security Policy connect-src header to be ignored. This could lead to connections to restricted origins from inside WebWorkers. This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more

CVE-2023-23601

URL being dragged from cross-origin iframe into same tab triggers navigation

Navigations were being allowed when dragging a URL from a cross-origin iframe into the same tab which could lead to website spoofing attacks This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more

CVE-2023-23599

Malicious command could be hidden in devtools output on Windows

When copying a network request from the developer tools panel as a curl command the output was not being properly sanitized and could allow arbitrary commands to be hidden within. This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Mozilla Redhat

Products

Firefox Firefox Esr Thunderbird and 5 more