Mozilla vulnerabilities
We track 912 vulnerabilities in Mozilla products across 22 products. 911 are rated high or critical, and 15 have been exploited in real attacks. The most recent was published on November 10, 2026.
Latest Mozilla vulnerabilities
- 8.8 High severity
Firefox: Concurrent Execution using Shared Resource with Improper Synchronization
When a worker is shutdown, it was possible to cause script to run late in the lifecycle, at a point after where it should not be possible. This vulnerability affects Firefox < 96, Thunderbird < 91.6, and Firefox ESR < 91.6.
- 8.8 High severity
Firefox: Protection Mechanism Failure
Web-accessible extension pages (pages with a moz-extension:// scheme) were not correctly enforcing the frame-ancestors directive when it was used in the Web Extension's Content Security Policy. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and F
- 9.6 Critical severity
Firefox: Protection Mechanism Failure
If a document created a sandboxed iframe without <code>allow-scripts</code>, and subsequently appended an element to the iframe's document that e.g. had a JavaScript event handler - the event handler would have run despite the iframe's sandbox. This vulnerabil
- 8.8 High severity
Firefox: Cleartext Transmission of Sensitive Information
When clicking on a tel: link, USSD codes, specified after a <code>\*</code> character, would be included in the phone number. On certain phones, or on certain carriers, if the number was dialed this could perform actions on a user's account, similar to a cross
- 8.8 High severity
Firefox: Improper Control of Generation of Code
If a user was convinced to drag and drop an image to their desktop or other folder, the resulting object could have been changed into an executable script which would have run arbitrary code after the user clicked on it. This vulnerability affects Firefox < 97
- 8.8 High severity
Firefox: Operation on a Resource after Expiration or Release
By using XSL Transforms, a malicious webserver could have served a user an XSL document that would continue to execute JavaScript (within the bounds of the same-origin policy) even after the tab was closed. This vulnerability affects Firefox < 97.
- 7.1 High severity
Firefox: Time-of-check Time-of-use (TOCTOU) Race Condition
A Time-of-Check Time-of-Use bug existed in the Maintenance (Updater) Service that could be abused to grant Users write access to an arbitrary directory. This could have been used to escalate to SYSTEM access.<br>*This bug only affects Firefox on Windows. Other
- 8.8 High severity
Firefox: Out-of-bounds Write
Mozilla developers Christian Holler and Jason Kratzer reported memory safety bugs present in Firefox 95. 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 cod
- 8.8 High severity
Firefox ESR: Out-of-bounds Write
Mozilla developers Calixte Denizet, Kershaw Chang, Christian Holler, Jason Kratzer, Gabriele Svelto, Tyson Smith, Simon Giesecke, and Steve Fink reported memory safety bugs present in Firefox 95 and Firefox ESR 91.4. Some of these bugs showed evidence of memor
- 8.8 High severity
Firefox ESR: Improper Encoding or Escaping of Output
The constructed curl command from the "Copy as curl" feature in DevTools was not properly escaped for PowerShell. This could have lead to command injection if pasted into a Powershell prompt.<br>*This bug only affects Thunderbird for Windows. Other operating s
- 8.8 High severity
Firefox ESR: Use After Free
Certain network request objects were freed too early when releasing a network request handle. This could have lead to a use-after-free causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.
- 8.8 High severity
Firefox ESR: Out-of-bounds Write
Applying a CSS filter effect could have accessed out of bounds memory. This could have lead to a heap-buffer-overflow causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.
- 7.5 High severity
Firefox ESR: Concurrent Execution using Shared Resource with Improper Synchronization
Constructing audio sinks could have lead to a race condition when playing audio files and closing windows. This could have lead to a use-after-free causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunde
- 7.0 High severity
Firefox: Uncontrolled Search Path Element
If Firefox was installed to a world-writable directory, a local privilege escalation could occur when Firefox searched the current directory for system libraries. However the install directory is not world-writable by default.<br>*This bug only affects Firefox
- 8.8 High severity
Firefox ESR: Improperly Controlled Modification of Object Prototype Attributes
If an attacker was able to corrupt the methods of an Array object in JavaScript via prototype pollution, they could have achieved execution of attacker-controlled JavaScript code in a privileged context. This vulnerability affects Firefox ESR < 91.9.1, Firefox
- 8.8 High severity
Firefox ESR: Improperly Controlled Modification of Object Prototype Attributes
An attacker could have sent a message to the parent process where the contents were used to double-index into a JavaScript object, leading to prototype pollution and ultimately attacker-controlled JavaScript executing in the privileged parent process. This vul
- 8.8 High severity
Firefox: Out-of-bounds Write
Mozilla developers Kershaw Chang, Ryan VanderMeulen, and Randell Jesup reported memory safety bugs present in Firefox 97. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to
- 8.8 High severity
Thunderbird: Out-of-bounds Write
It may be possible for an attacker to craft an email message that causes Thunderbird to perform an out-of-bounds write of one byte when processing the message. This vulnerability affects Thunderbird < 91.6.1.
- 7.8 High severity
Mozilla VPN: Unrestricted Upload of File with Dangerous Type
Mozilla VPN can load an OpenSSL configuration file from an unsecured directory. A user or attacker with limited privileges could leverage this to launch arbitrary code with SYSTEM privilege. This vulnerability affects Mozilla VPN < 2.7.1.
- 8.8 High severity
Firefox: Out-of-bounds Write
Mozilla developers and community members Gabriele Svelto, Sebastian Hengst, Randell Jesup, Luan Herrera, Lars T Hansen, and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 96. Some of these bugs showed evidence of memory corruption and
- 8.2 High severity
onion: Improper Resource Shutdown or Release
A vulnerability was found in davidmoreno onion. It has been rated as problematic. Affected by this issue is the function onion_response_flush of the file src/onion/response.c of the component Log Handler. The manipulation leads to allocation of resources. The
- 7.5 High severity
hawk: Inefficient Regular Expression Complexity
Hawk is an HTTP authentication scheme providing mechanisms for making authenticated HTTP requests with partial cryptographic verification of the request and response, covering the HTTP method, request URI, host, and optionally the request payload. Hawk used a
- 8.1 High severity
Mozilla Firefox And Thunderbird Use-After-Free Exploited
Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.
- 8.1 High severity
Mozilla Firefox And Thunderbird Use-After-Free Exploited
Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR <
- 8.8 High severity
Mozilla Firefox And Thunderbird Type Confusion Exploited
Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox
- 10.0 Critical severity
Mozilla Firefox and Thunderbird Sandbox Escape Exploited
Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxed parent process opening web content chosen by a compromised child process. When combined with additional vulnerabilitie
- 8.8 High severity
Mozilla Firefox and Thunderbird Type Confusion Exploited
A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1,
- 7.5 High severity
Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Exploited
A use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Firefox ESR < 45.5.1, a
- 8.8 High severity
Mozilla Firefox Security Feature Bypass Exploited
The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypass the Same Origin Policy, and read arbitrary files or gain privileges, via vectors involving crafted JavaScript code and
- 8.8 High severity
Mozilla Firefox and Thunderbird Denial-of-Service Exploited
Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not properly handle onreadystatechange events in conjunction with page reloading, which allows remote attackers to cause a denial
- 6.5 Medium severity
Mozilla Firefox Information Disclosure Exploited
Mozilla Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6 do not properly initialize data structures for the nsDOMSVGZoomEvent::mPreviousScale and nsDOMSVGZoomEvent::mNewScale functions, whic
- 9.3 High severity
Mozilla Multiple Products Remote Code Execution Exploited
Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x before 2.0.10, when JavaScript is enabled, allows remote attackers to execute arbitrary code via vectors related to nsCSSFr