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.

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.

Long hostnames in URLs could be leveraged to obscure the actual host of the website or spoof the website address. This vulnerability was fixed in Firefox for iOS 134.

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.

An attacker could have abused XSLT error handling to associate attacker-controlled content with another origin which was displayed in the address bar. This could have been used to fool the user into submitting data intended for the spoofed origin. This vulnerability affects Thunderbird < 102.2, Thunderbird < 91.13, Firefox ESR < 91.13, Firefox ESR < 102.2, and Firefox < 104.

Through complicated navigations with new windows, an HTTP page could have inherited a secure lock icon from an HTTPS page. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Same-origin policy bypass in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 148.0.2.

Thunderbird displayed an incorrect sender address if the From field of an email used the invalid group name syntax that is described in CVE-2024-49040. This vulnerability was fixed in Thunderbird 128.7 and Thunderbird 135.

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.

When a link to an external protocol was clicked, a prompt was presented that allowed the user to choose what application to open it in. An attacker could induce that prompt to be associated with an origin they didn't control, resulting in a spoofing attack. This was fixed by changing external protocol prompts to be tab-modal while also ensuring they could not be incorrectly associated with a different origin. This vulnerability affects Firefox < 82.

When downloading an update for an addon, the downloaded addon update's version was not verified to match the version selected from the manifest. If the manifest had been tampered with on the server, an attacker could trick the browser into downgrading the addon to a prior version. This vulnerability affects Firefox < 102.

Through use of reportValidity() and window.open(), a plain-text validation message could have been overlaid on another origin, leading to possible user confusion and spoofing attacks. This vulnerability affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.

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.

Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird < 91.4.0.

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.

Mixed-content checks were unable to analyze opaque origins which led to some mixed content being loaded. This vulnerability affects Firefox < 92.

A flaw in Mozilla's embedded certificate code might allow web sites to install root certificates on devices without user approval.

When a secure cookie existed in the Firefox cookie jar an insecure cookie for the same domain could have been created, when it should have silently failed. This could have led to a desynchronization in expected results when reading from the secure cookie. This vulnerability affects Firefox for Android < 112, Firefox < 112, and Focus for Android < 112.

A wrong lowering instruction in the ARM64 Ion compiler resulted in a wrong optimization result. This vulnerability affects Firefox < 112, Focus for Android < 112, Firefox ESR < 102.10, Firefox for Android < 112, and Thunderbird < 102.10.

Under certain circumstances, a call to the <code>bind</code> function may have resulted in the incorrect realm. This may have created a vulnerability relating to JavaScript-implemented sandboxes such as SES. This vulnerability affects Firefox for Android < 112, Firefox < 112, and Focus for Android < 112.

Similar to CVE-2023-28163, this time when choosing 'Save Link As', suggested filenames containing environment variable names would have resolved those in the context of the current user. *This bug only affects Firefox and Thunderbird on Windows. Other versions of Firefox and Thunderbird are unaffected.* This vulnerability affects Firefox < 112, Firefox ESR < 102.10, and Thunderbird < 102.10.

When downloading files through the Save As dialog on Windows with suggested filenames containing environment variable names, Windows would have resolved those in the context of the current user. <br>*This bug only affects Firefox on Windows. Other versions of Firefox are unaffected.*. This vulnerability affects Firefox < 111, Firefox ESR < 102.9, and Thunderbird < 102.9.

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.

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.

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.

A duplicate `SystemPrincipal` object could be created when parsing a non-system html document via `DOMParser::ParseFromSafeString`. This could have lead to bypassing web security checks. This vulnerability affects Firefox < 109.

Unicode RTLO characters could allow malicious websites to spoof filenames in the downloads UI for Firefox for iOS, potentially tricking users into saving files of an unexpected file type. This vulnerability was fixed in Firefox for iOS 144.0.

Certificate OCSP revocation status was not checked when verifying S/Mime signatures. Mail signed with a revoked certificate would be displayed as having a valid signature. Thunderbird versions from 68 to 102.7.0 were affected by this bug. This vulnerability affects Thunderbird < 102.7.1.

An attacker could have injected CSS into stylesheets accessible via internal URIs, such as resource:, and in doing so bypass a page's Content Security Policy. This vulnerability affects Firefox ESR < 91.11, Thunderbird < 102, Thunderbird < 91.11, and Firefox < 101.

Use tables inside of an iframe, an attacker could have caused iframe contents to be rendered outside the boundaries of the iframe, resulting in potential user confusion or spoofing attacks. This vulnerability affects Firefox ESR < 102.5, Thunderbird < 102.5, and Firefox < 107.

Firefox's HTML parser did not correctly interpret HTML comment tags, resulting in an incongruity with other browsers. This could have been used to escape HTML comments on pages that put user-controlled data in them. This vulnerability affects Firefox < 101.

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.

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 browsing private tabs, some data related to location history or webpage thumbnails could be persisted incorrectly within the sandboxed app bundle after app termination This vulnerability affects Firefox for iOS < 127.

An OpenPGP digital signature includes information about the date when the signature was created. When displaying an email that contains a digital signature, the email's date will be shown. If the dates were different, then Thunderbird didn't report the email as having an invalid signature. If an attacker performed a replay attack, in which an old email with old contents are resent at a later time, it could lead the victim to believe that the statements in the email are current. Fixed versions of Thunderbird will require that the signature's date roughly matches the displayed date of the email. This vulnerability affects Thunderbird < 102 and Thunderbird < 91.11.

Spoofing issue in the Toolbar component in Firefox for Android. This vulnerability was fixed in Firefox 151.

Spoofing issue in the Form Autofill component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

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.

If a user installed an extension of a particular type, the extension could have auto-updated itself and while doing so, bypass the prompt which grants the new version the new requested permissions. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and Firefox ESR < 91.6.

Focus was incorrectly allowing internal links to utilize the app scheme used for deeplinking, which could result in links potentially circumventing some URL safety checks This vulnerability affects Focus for iOS < 132.

Through a series of DOM manipulations, a message, over which the attacker had control of the text but not HTML or formatting, could be overlaid on top of another domain (with the new domain correctly shown in the address bar) resulting in possible user confusion. This vulnerability affects Firefox < 90.

When the address bar was hidden due to scrolling on Android, a malicious page could create a fake address bar to fool the user in response to a visibilitychange event. This vulnerability was fixed in Firefox 144.

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.

Links in a sandboxed iframe could open an external app on Android without the required "allow-" permission. This vulnerability was fixed in Firefox 144 and Thunderbird 144.

There was a way to change the value of JavaScript Object properties that were supposed to be non-writeable. This vulnerability was fixed in Firefox 144, Firefox ESR 115.29, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.

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.

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.

Using techniques that built on the slipstream research, a malicious webpage could have scanned both an internal network's hosts as well as services running on the user's local machine utilizing WebRTC connections. This vulnerability affects Firefox ESR < 78.9, Firefox < 87, and Thunderbird < 78.9.

The developer page about:memory has a Measure function for exploring what object types the browser has allocated and their sizes. When this function was invoked we incorrectly called the sizeof function, instead of using the API method that checks for invalid pointers. This vulnerability affects Firefox < 86.

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.