On pages containing an iframe, the "data:" protocol can be used to create a modal alert that will render over arbitrary domains following page navigation, spoofing of the origin of the modal alert from the iframe content. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

If a server sends two Strict-Transport-Security (STS) headers for a single connection, they will be rejected as invalid and HTTP Strict Transport Security (HSTS) will not be enabled for the connection. This vulnerability affects Firefox < 55.

An error in the "WindowsDllDetourPatcher" where a RWX ("Read/Write/Execute") 4k block is allocated but never protected, violating DEP protections. Note: This attack only affects Windows operating systems. Other operating systems are not affected. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

RSS fields can inject new lines into the created email structure, modifying the message body. This vulnerability affects Thunderbird < 52.5.2.

SVG loaded through "<img>" tags can use "<meta>" tags within the SVG data to set cookies for that page. This vulnerability affects Firefox < 57.

A spoofing vulnerability can occur when a page switches to fullscreen mode without user notification, allowing a fake address bar to be displayed. This allows an attacker to spoof which page is actually loaded and in use. Note: This attack only affects Firefox for Android. Other operating systems are not affected. This vulnerability affects Firefox < 56.

When a page's content security policy (CSP) header contains a "sandbox" directive, other directives are ignored. This results in the incorrect enforcement of CSP. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

Characters from the "Canadian Syllabics" unicode block can be mixed with characters from other unicode blocks in the addressbar instead of being rendered as their raw "punycode" form, allowing for domain name spoofing attacks through character confusion. The current Unicode standard allows characters from "Aspirational Use Scripts" such as Canadian Syllabics to be mixed with Latin characters in the "moderately restrictive" IDN profile. We have changed Firefox behavior to match the upcoming Unicode version 10.0 which removes this category and treats them as "Limited Use Scripts.". This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

Punycode format text will be displayed for entire qualified international domain names in some instances when a sub-domain triggers the punycode display instead of the primary domain being displayed in native script and the sub-domain only displaying as punycode. This could be used for limited spoofing attacks due to user confusion. This vulnerability affects Firefox < 57.

On pages containing an iframe, the "data:" protocol can be used to create a modal dialog through Javascript that will have an arbitrary domains as the dialog's location, spoofing of the origin of the modal dialog from the user view. Note: This attack only affects installations with e10 multiprocess turned off. Installations with e10s turned on do not support the modal dialog functionality. This vulnerability affects Firefox < 56.

The combined, single character, version of the letter 'i' with any of the potential accents in unicode, such as acute or grave, can be spoofed in the addressbar by the dotless version of 'i' followed by the same accent as a second character with most font sets. This allows for domain spoofing attacks because these combined domain names do not display as punycode. This vulnerability affects Firefox < 57.

Mozilla Firefox 4.x through 9.0, Thunderbird 5.0 through 9.0, and SeaMonkey before 2.7 allow remote attackers to bypass the HTML5 frame-navigation policy and replace arbitrary sub-frames by creating a form submission target with a sub-frame's name attribute.

A flaw in DRBG number generation within the Network Security Services (NSS) library where the internal state V does not correctly carry bits over. The NSS library has been updated to fix this issue to address this issue and Firefox ESR 52.1 has been updated with NSS version 3.28.4. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.

The "export" function in the Certificate Viewer can force local filesystem navigation when the "common name" in a certificate contains slashes, allowing certificate content to be saved in unsafe locations with an arbitrary filename. This vulnerability affects Firefox < 51.

On Linux, if the secure computing mode BPF (seccomp-bpf) filter is running when the Gecko Media Plugin sandbox is started, the sandbox fails to be applied and items that would run within the sandbox are run protected only by the running filter which is typically weak compared to the sandbox. Note: this issue only affects Linux. Other operating systems are not affected. This vulnerability affects Firefox < 52 and Thunderbird < 52.

A mechanism to spoof the Firefox for Android addressbar using a "javascript:" URI. On Firefox for Android, the base domain is parsed incorrectly, making the resulting location less visibly a spoofed site and showing an incorrect domain in appended notifications. This vulnerability affects Firefox < 53.

An attack can use a blob URL and script to spoof an arbitrary addressbar URL prefaced by "blob:" as the protocol, leading to user confusion and further spoofing attacks. This vulnerability affects Firefox < 52.

A malicious site could spoof the contents of the print preview window if popup windows are enabled, resulting in user confusion of what site is currently loaded. This vulnerability affects Firefox < 52 and Thunderbird < 52.

Android intents can be used to launch Firefox for Android in reader mode with a user specified URL. This allows an attacker to spoof the contents of the addressbar as displayed to users. Note: This attack only affects Firefox for Android. Other operating systems are not affected. This vulnerability affects Firefox < 53.

Firefox before 1.0.7 and Mozilla Suite before 1.7.12 allows remote attackers to modify HTTP headers of XML HTTP requests via XMLHttpRequest, and possibly use the client to exploit vulnerabilities in servers or proxies, including HTTP request smuggling and HTTP request splitting.

Mozilla Firefox before 5.0 does not properly enforce the whitelist for the xpinstall functionality, which allows remote attackers to trigger an installation dialog for a (1) add-on or (2) theme via unspecified vectors.

A malicious website that causes an HTTP Authentication dialog to be spawned could trick the built-in password manager to suggest passwords for the currently active website instead of the website that triggered the dialog. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 89.

If a site is loaded over a HTTPS connection but loads a favicon resource over HTTP, the mixed content warning is not displayed to users. This vulnerability affects Firefox < 63.

Bugzilla 2.16rc1 through 2.22.7, 3.0.x through 3.3.x, 3.4.x before 3.4.12, 3.5.x, 3.6.x before 3.6.6, 3.7.x, 4.0.x before 4.0.2, and 4.1.x before 4.1.3 does not prevent changes to the confirmation e-mail address (aka old_email field) for e-mail change notifications, which makes it easier for remote attackers to perform arbitrary address changes by leveraging an unattended workstation.

The displayed addressbar URL can be spoofed on Firefox for Android using a javascript: URI in concert with JavaScript to insert text before the loaded domain name, scrolling the loaded domain out of view to the right. This can lead to user confusion. *This vulnerability only affects Firefox for Android < 62.*

Manually dragging and dropping an Outlook email message into the browser will trigger a page navigation when the message's mail columns are incorrectly interpreted as a URL. *Note: this issue only affects Windows operating systems with Outlook installed. Other operating systems are not affected.*. This vulnerability affects Firefox ESR < 60.2 and Firefox < 62.

Mozilla Firefox before 3.6.18, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 do not distinguish between cookies for two domain names that differ only in a trailing dot, which allows remote web servers to bypass the Same Origin Policy via Set-Cookie headers.

When a new Firefox profile is created on 64-bit Windows installations, the sandbox for 64-bit NPAPI plugins is not enabled by default. Note: This issue only affects 64-bit Windows. 32-bit Windows and other operating systems are unaffected. This vulnerability affects Firefox < 50.

The location bar in Firefox for Android can be spoofed by forcing a user into fullscreen mode, blocking its exiting, and creating of a fake location bar without any user notification. Note: This issue only affects Firefox for Android. Other versions and operating systems are unaffected. This vulnerability affects Firefox < 50.

The "instanceof" operator can bypass the Xray wrapper mechanism. When called on web content from the browser itself or an extension the web content can provide its own result for that operator, possibly tricking the browser or extension into mishandling the element. This vulnerability affects Firefox < 56.

Some Arabic and Indic vowel marker characters can be combined with Latin characters in a domain name to eclipse the non-Latin character with some font sets on the addressbar. The non-Latin character will not be visible to most viewers. This allows for domain spoofing attacks because these combined domain names do not display as punycode. This vulnerability affects Firefox < 57.

When entered directly, Reader Mode did not strip the username and password section of URLs displayed in the addressbar. This can be used for spoofing the domain of the current page. This vulnerability affects Firefox < 54.

It is possible to spoof the sender's email address and display an arbitrary sender address to the email recipient. The real sender's address is not displayed if preceded by a null character in the display string. This vulnerability affects Thunderbird < 52.5.2.

Default fonts on OS X display some Tibetan characters as whitespace. When used in the addressbar as part of an IDN this can be used for domain name spoofing attacks. Note: This attack only affects OS X operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

The destructor function for the "WindowsDllDetourPatcher" class can be re-purposed by malicious code in concert with another vulnerability to write arbitrary data to an attacker controlled location in memory. This can be used to bypass existing memory protections in this situation. Note: This attack only affects Windows operating systems. Other operating systems are not affected. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

URLs containing certain unicode glyphs for alternative hyphens and quotes do not properly trigger punycode display, allowing for domain name spoofing attacks in the location bar. This vulnerability affects Thunderbird < 45.7, Firefox ESR < 45.7, and Firefox < 51.

Incorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

When dragging content from the primary browser pane to the addressbar on a malicious site, it is possible to change the addressbar so that the displayed location following navigation does not match the URL of the newly loaded page. This allows for spoofing attacks. This vulnerability affects Firefox < 52.

The internal feed reader APIs that crossed the sandbox barrier allowed for a sandbox escape and escalation of privilege if combined with another vulnerability that resulted in remote code execution inside the sandboxed process. This vulnerability affects Firefox ESR < 52.1 and Firefox < 53.

Mozilla Firefox before 44.0 on Android allows remote attackers to spoof the address bar via a data: URL that is mishandled during (1) shortcut opening or (2) BOOKMARK intent processing.

Mozilla Firefox before 43.0 mishandles the # (number sign) character in a data: URI, which allows remote attackers to spoof web sites via unspecified vectors.

Mozilla Firefox before 42.0 and Firefox ESR 38.x before 38.4 improperly control the ability of a web worker to create a WebSocket object, which allows remote attackers to bypass intended mixed-content restrictions via crafted JavaScript code.

Mozilla Firefox before 40.0 and Firefox ESR 38.x before 38.2 do not impose certain ECMAScript 6 requirements on JavaScript object properties, which allows remote attackers to bypass the Same Origin Policy via the reviver parameter to the JSON.parse method.

Mozilla Firefox before 2.0.0.13 and SeaMonkey before 1.1.9, when generating the HTTP Referer header, does not list the entire URL when it contains Basic Authentication credentials without a username, which makes it easier for remote attackers to bypass application protection mechanisms that rely on Referer headers, such as with some Cross-Site Request Forgery (CSRF) mechanisms.

When protecting CSS blocks with the nonce feature of Content Security Policy, the @import statement in the CSS block could allow an attacker to inject arbitrary styles, bypassing the intent of the Content Security Policy. This vulnerability affects Firefox < 74.

The Reader mode feature in Mozilla Firefox before 37.0.1 on Android, and Desktop Firefox pre-release, does not properly handle privileged URLs, which makes it easier for remote attackers to execute arbitrary JavaScript code with chrome privileges by leveraging the ability to bypass the Same Origin Policy.

The "Mark of the Web" was not correctly saved on Windows when files with very long names were downloaded from the Internet. Without the Mark of the Web data, the security warning that Windows displays before running executables downloaded from the Internet is not shown. Note: This attack only affects Windows operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

email_in.pl in Bugzilla 2.23.4 through 3.0.0 allows remote attackers to execute arbitrary commands via the -f (From address) option to the Email::Send::Sendmail function, probably involving shell metacharacters.

Mozilla Firefox 2.0.0.1 through 2.0.0.3 does not canonicalize URLs before checking them against the phishing site blacklist, which allows remote attackers to bypass phishing protection via multiple / (slash) characters in the URL.

The fullscreen notification is prematurely hidden when fullscreen is re-requested quickly by the user. This could have been leveraged to perform a potential spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.