The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection to be transparently upgraded to TLS while retaining the visual properties of an HTTP connection, including being same-origin with unencrypted connections on port 80. However, if a second encrypted port on the same IP address (e.g. port 8443) did not opt-in to opportunistic encryption; a network attacker could forward a connection from the browser to port 443 to port 8443, causing the browser to treat the content of port 8443 as same-origin with HTTP. This was resolved by disabling the Opportunistic Encryption feature, which had low usage. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
The executable file warning was not presented when downloading .msix, .msixbundle, .appx, and .appxbundle files, which can run commands on a user's computer. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 119, Firefox ESR < 115.4, and Thunderbird < 115.4.1.
When an https: web page created a pop-up from a "javascript:" URL, that pop-up was incorrectly allowed to load blockable content such as iframes from insecure http: URLs This vulnerability affects Firefox < 120.
If an attacker needed a user to load an insecure http: page and knew that user had enabled HTTPS-only mode, the attacker could have tricked the user into clicking to grant an HTTPS-only exception if they could get the user to participate in a clicking game. This vulnerability affects Firefox < 120.
An attacker could have created a malicious link using bidirectional characters to spoof the location in the address bar when visited. This vulnerability affects Firefox < 117, Firefox ESR < 115.4, and Thunderbird < 115.4.1.
Firefox for Android could get stuck in fullscreen mode and not exit it even after normal interactions that should cause it to exit. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91.
A `<dialog>` element could have been manipulated to paint content outside of a sandboxed iframe. This could allow untrusted content to display under the guise of trusted content. This vulnerability affects Firefox < 121.
When browsing a document hosted on an IP address, an attacker could insert certain characters to flip domain and path information in the address bar. This vulnerability affects Firefox < 77.
When constructing a permission prompt for WebRTC, a URI was supplied from the content process. This URI was untrusted, and could have been the URI of an origin that was previously granted permission; bypassing the prompt. This vulnerability affects Firefox < 78.
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.
By utilizing 3D CSS in conjunction with Javascript, content could have been rendered outside the webpage's viewport, resulting in a spoofing attack that could have been used for phishing or other attacks on a user. This vulnerability affects Firefox < 88.
IndexedDB should be cleared when leaving private browsing mode and it is not, the API for WKWebViewConfiguration was being used incorrectly and requires the private instance of this object be deleted when leaving private mode. This vulnerability affects Firefox for iOS < 27.
A malicious extension could have opened a popup window lacking an address bar. The title of the popup lacking an address bar should not be fully controllable, but in this situation was. This could have been used to spoof a website and attempt to trick the user into providing credentials. This vulnerability affects Firefox ESR < 78.9, Firefox < 87, and Thunderbird < 78.9.
When "%2F" was present in a manifest URL, Firefox's AppCache behavior may have become confused and allowed a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory. This vulnerability affects Firefox < 78.
OCSP revocation status of recipient certificates was not checked when sending S/Mime encrypted email, and revoked certificates would be accepted. Thunderbird versions from 68 to 102.9.1 were affected by this bug. This vulnerability affects Thunderbird < 102.10.
The "Forget about this site" feature in the History pane is intended to remove all saved user data that indicates a user has visited a site. This includes removing any HTTP Strict Transport Security (HSTS) settings received from sites that use it. Due to a bug, sites on the pre-load list also have their HSTS setting removed. On the next visit to that site if the user specifies an http: URL rather than secure https: they will not be protected by the pre-loaded HSTS setting. After that visit the site's HSTS setting will be restored. This vulnerability affects Firefox < 69 and Firefox ESR < 68.1.
Spoofing issue in the Address Bar component of Firefox Focus for Android. This vulnerability affects Firefox < 142.
Firefox before 1.0.1 and Mozilla before 1.7.6 allows remote malicious web sites to overwrite arbitrary files by tricking the user into downloading a .LNK (link) file twice, which overwrites the file that was referenced in the first .LNK file.
Spoofing issue in the Address Bar component. This vulnerability affects Firefox < 142 and Firefox ESR < 140.2.
When a JavaScript URL (javascript:) is evaluated and the result is a string, this string is parsed to create an HTML document, which is then presented. Previously, this document's URL (as reported by the document.location property, for example) was the originating javascript: URL which could lead to spoofing attacks; it is now correctly the URL of the originating document. This vulnerability affects Firefox < 74.
When a link can be opened in an external application, Firefox for Android will, by default, prompt the user before doing so. An attacker could have bypassed this prompt, potentially exposing the user to security vulnerabilities or privacy leaks in external applications. *This bug only affects Firefox for Android. Other versions of Firefox are unaffected.* This vulnerability affects Firefox < 140.
Firefox could have incorrectly parsed a URL and rewritten it to the youtube.com domain when parsing the URL specified in an `embed` tag. This could have bypassed website security checks that restricted which domains users were allowed to embed. This vulnerability affects Firefox < 140, Firefox ESR < 128.12, Thunderbird < 140, and Thunderbird < 128.12.
A website could have obscured the full screen notification by using a URL with a scheme handled by an external program, such as a mailto URL. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 116, Firefox ESR < 115.2, and Thunderbird < 115.2.
By attempting to connect a website using an unresponsive port, an attacker could have controlled the content of a tab while the URL bar displayed the original domain. *Note: This issue only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.
OneCRL was non-functional in the new Firefox for Android due to a missing service initialization. This could result in a failure to enforce some certificate revocations. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.
When a HTTPS pages was embedded in a HTTP page, and there was a service worker registered for the former, the service worker could have intercepted the request for the secure page despite the iframe not being a secure context due to the (insecure) framing. This vulnerability affects Firefox < 84.
When listening for page changes with a Mutation Observer, a malicious web page could confuse Firefox Screenshots into interacting with elements other than those that it injected into the page. This would lead to internal errors and unexpected behavior in the Screenshots code. This vulnerability affects Firefox < 83.
When a malicious application installed on the user's device broadcast an Intent to Firefox for Android, arbitrary headers could have been specified, leading to attacks such as abusing ambient authority or session fixation. This was resolved by only allowing certain safe-listed headers. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.
When a user downloaded a file in Firefox for Android, if a cookie is set, it would have been re-sent during a subsequent file download operation on the same domain, regardless of whether the original and subsequent request were in private and non-private browsing modes. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.
By injecting a cookie with certain special characters, an attacker on a shared subdomain which is not a secure context could set and thus overwrite cookies from a secure context, leading to session fixation and other attacks. This vulnerability affects Firefox ESR < 102.3, Thunderbird < 102.3, and Firefox < 105.
The use of RTL Arabic characters in the address bar may have allowed for URL spoofing. This vulnerability affects Firefox < 115.
A website could have obscured the fullscreen notification by using a URL with a scheme handled by an external program, such as a mailto URL. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 115, Firefox ESR < 102.13, and Thunderbird < 102.13.
A website could prevent a user from exiting full-screen mode via alert and prompt calls. This could lead to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 115.
A website could have obscured the fullscreen notification by using an option element by introducing lag via an expensive computational function. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 115.
Dragging a URL from a cross-origin iframe that was removed during the drag could have led to user confusion and website spoofing attacks. This vulnerability affects Firefox < 111, Firefox ESR < 102.9, and Thunderbird < 102.9.
After a HelloRetryRequest has been sent, the client may negotiate a lower protocol that TLS 1.3, resulting in an invalid state transition in the TLS State Machine. If the client gets into this state, incoming Application Data records will be ignored. This vulnerability affects Firefox < 72.
If an XML file is served with a Content Security Policy and the XML file includes an XSL stylesheet, the Content Security Policy will not be applied to the contents of the XSL stylesheet. If the XSL sheet e.g. includes JavaScript, it would bypass any of the restrictions of the Content Security Policy applied to the XML document. This vulnerability affects Firefox < 72.
Long hostnames in URLs could be leveraged to obscure the actual host of the website or spoof the website address This vulnerability affects Firefox for iOS < 134.
When reusing existing popups Firefox would have allowed them to cover the fullscreen notification UI, which could have enabled browser spoofing attacks. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
The parent process would not properly check whether the Speech Synthesis feature is enabled, when receiving instructions from a child process. This vulnerability affects Thunderbird < 91.9.
Documents were incorrectly assuming an ordering of principal objects when ensuring we were loading an appropriately privileged principal. In certain circumstances it might have been possible to cause a document to be loaded with a higher privileged principal than intended. This vulnerability affects Firefox < 113.
The date picker could partially obscure security prompts. This could be used by a malicious site to trick a user into granting permissions. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, and Thunderbird < 115.14.
Select options could obscure the fullscreen notification dialog. This could be used by a malicious site to perform a spoofing attack. This vulnerability affects Firefox < 129, Firefox ESR < 128.1, and Thunderbird < 128.1.
A compromised content process could send a message to the parent process that would cause the 'Click to Play' permission prompt to be shown. However, due to lack of validation from the parent process, if the user accepted the permission request an attacker-controlled permission would be granted rather than the 'Click to Play' permission. This vulnerability affects Firefox < 70.
A same-origin policy violation occurs allowing the theft of cross-origin images through a combination of SVG filters and a <canvas> element due to an error in how same-origin policy is applied to cached image content. The resulting same-origin policy violation could allow for data theft. This vulnerability affects Firefox < 69, Thunderbird < 68.1, Thunderbird < 60.9, Firefox ESR < 60.9, and Firefox ESR < 68.1.
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.
The unicode latin 'kra' character can be used to spoof a standard 'k' character in the addressbar. This allows for domain spoofing attacks as do not display as punycode text, allowing for user confusion. This vulnerability affects Firefox < 68.
Malicious websites could have confused Firefox into showing the wrong origin when asking to launch a program and handling an external URL protocol. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.
A flaw in Mozilla's embedded certificate code might allow web sites to install root certificates on devices without user approval.