onUnload + document.write() memory corruption — Mozilla

Michal Zalewski reported a memory corruption vulnerability in Firefox 2.0.0.1 involving mixing the onUnload event handler and self-modifying document.write calls. This flaw was introduced in Firefox 2.0.0.1 and 1.5.0.9 and does not affect earlier versions; it is fixed in Firefox 2.0.0.2 and 1.5.0...

Spoofing using custom cursor and CSS3 hotspot — Mozilla

David Eckel reported that browser UI elements--such as the host name and security indicators--could be spoofed by using a large, mostly transparent, custom cursor and adjusting the CSS3 hotspot property so that the visible part of the cursor floated outside the browser content area...

JavaScript engine vulnerabilities — Mozilla

Continuing our security audit of the JavaScript engine, Mozilla developers found and fixed several potential vulnerabilities...

Privilege escalation using named-functions and redefined "new Object()" — Mozilla

mozbugra4 discovered that named JavaScript functions have a parent object created using the standard Object constructor ECMA-specified behavior and that this constructor can be redefined by script also ECMA-specified behavior. If the Object constructor is changed to return a reference to a...

Buffer overflow in crypto.signText() — Mozilla

Mikolaj Habryn discovered an array index bug in crypto.signText that results in overflowing an allocated array of pointers by two when optional Certificate Authority name arguments are passed in...

EvalInSandbox escape (Proxy Autoconfig, Greasemonkey) — Mozilla

Mozilla researcher mozbugra4 demonstrated that javascript run via EvalInSandbox can escape the sandbox and gain elevated privilege by calling valueOf on objects created outside the sandbox and inserted into it. Malicious scripts could use these privileges to compromise your computer or data...

Mail Multiple Information Disclosure — Mozilla

As a privacy measure to prevent senders primarily spammers from tracking when e-mail is read Thunderbird does not load remote content referenced from an HTML mail message until a user tells it to do so. This normally includes the content of frames and CSS files, but CrashFr showed it was possible...

Drag and drop loading of privileged XUL — Mozilla

A malicious page that could lure a user into dragging something such as a fake scrollbar can bypass the restriction on opening privileged XUL. The startup scripts in the XUL will run with enhanced privilege, though the actions taken upon merely opening most XUL are benign. So far no way to run...

GIF heap overflow parsing Netscape extension 2 — Mozilla

An GIF processing error when parsing the obsolete Netscape extension 2 can lead to an exploitable heap overrun, allowing an attacker to run arbitrary code on the user's machine...

Security Vulnerabilities fixed in Firefox for iOS 151.2 — Mozilla

Firefox for iOS Reader View replaced page content in its HTML template before replacing other internal placeholders. A malicious page could include a placeholder string that was later substituted with JSON-LD data, potentially resulting in arbitrary JavaScript execution. Firefox for iOS Reader Vi...

Security Vulnerability fixed in Firefox 136.0.4, Firefox ESR 128.8.1, Firefox ESR 115.21.1 — Mozilla

Following the recent Chrome sandbox escape CVE-2025-2783, various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was...

Security Vulnerabilities fixed in Thunderbird 115.13 — Mozilla

An error in the ECMA-262 specification relating to Async Generators could have resulted in a type confusion, potentially leading to memory corruption and an exploitable crash. Due to large allocation checks in Angle for GLSL shaders being too lenient an out-of-bounds access could occur when...

Security Vulnerabilities fixed in Firefox ESR 102.14 — Mozilla

Offscreen Canvas did not properly track cross-origin tainting, which could have been used to access image data from another site in violation of same-origin policy. In some circumstances, a stale value could have been used for a global variable in WASM JIT analysis. This resulted in incorrect...

Security Vulnerabilities fixed in Firefox ESR 102.13 — Mozilla

An attacker could have triggered a use-after-free condition when creating a WebRTC connection over HTTPS. Cross-compartment wrappers wrapping a scripted proxy could have caused objects from other compartments to be stored in the main compartment resulting in a use-after-free. A website could have...

Security Vulnerabilities fixed in Firefox for iOS 101 — Mozilla

The search term could have been specified externally to trigger SQL injection...

Security Vulnerabilities fixed in Firefox for iOS 34 — Mozilla

When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode...

Use-after-free when using multiple WebRTC data channels — Mozilla

Security researcher Dominique Hazaël-Massieux reported a use-after-free issue when using multiple WebRTC data channel connections. This causes a potentially exploitable crash when a data channel connection is freed from within a call through it...

CSP reports fail to strip location information for embedded iframe pages — Mozilla

Security researcher Muneaki Nishimura nishimunea of Recruit Technologies Co.,Ltd. reported that Content Security Policy CSP violation reports contained full path information for cross-origin iframe navigations in violation of the CSP specification. This could result in information disclosure...

HTML injection in homescreen app bypassing DOM sanitizer — Mozilla

Mozilla fixed a bug in the l10n localization of the default homescreen app of Firefox OS reported by security researcher Muneaki Nishimura. Exploiting this issue requires tricking the user into bookmarking a specially crafted web page via the 'Add to home screen' functionality. As a result, an...

Site attribute spoofing on Android by pasting URL with unknown scheme — Mozilla

Security researcher Jordi Chancel reported that on Firefox for Android, when a URL is pasted with an unknown protocol, such as secure: or httpz:, the pasted URL is shown in the addressbar but no navigation occurs. Other addressbar attributes present before this pasted URL is entered will continue...

Out-of-bounds read during 2D canvas display on Linux 16-bit color depth systems — Mozilla

Security researcher Francisco Alonso of the NowSecure Research Team used the Address Sanitizer tool to discover an out-of-bounds read issue during 2D canvas rendering. This was due to an issue in the cairo graphics library when surfaces are created with 32-bit color depth but displayed on a 16-bi...

OS X crash reports may contain entered key press information — Mozilla

Mozilla developer David Parks discovered while reviewing Firefox crash reports that personal data can sometimes be contained in reports from OS X systems. This is because these OS X crash reports will contain the native key that triggered the crash and this can sometimes contain key press...

Out-of-bounds write in Cairo — Mozilla

Security researcher Jukka Jylänki reported a crash in the the Cairo graphics library. This happens when Cairo paints out-of-bounds to the destination buffer in the compositing function when working with canvas in certain circumstances. This issue allows malicious web content to cause a potentiall...

Use-after-free in Vibrate — Mozilla

Security researcher regenrecht reported, via TippingPoint's Zero Day Initiative, a use-after-free using the domDoc pointer within Vibrate library. This can lead to arbitrary code execution when exploited...

Use-after-free error using Web Workers — Mozilla

Daniel Kozlowski reported that a JavaScript Worker could be used to keep a reference to an object that could be freed during garbage collection. Subsequent calls through this deleted reference could cause attacker-controlled memory to be executed on a victim's computer...

Information leak via XMLHttpRequest statusText — Mozilla

Matt Haggard reported that the statusText property of an XMLHttpRequest object is readable by the requester even when the request is made across origins. This status information reveals the presence of a web server and could be used to gather information about servers on internal private networks...

WOFF heap corruption due to integer overflow — Mozilla

Security researcher Evgeny Legerov of Intevydis reported that the WOFF decoder contains an integer overflow in a font decompression routine. This flaw could result in too small a memory buffer being allocated to store a downloadable font. An attacker could use this vulnerability to crash a victim...

Crashes with evidence of memory corruption (rv:1.9.1.2/1.9.0.13) — Mozilla

Mozilla developers and community members identified and fixed several stability bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these crashes showed evidence of memory corruption under certain circumstances and we presume that with enough effort at least some ...

Errors parsing URLs with leading whitespace and control characters — Mozilla

Perl developer Chip Salzenberg reported that certain control characters, when placed at the beginning of a URL, would lead to incorrect parsing resulting in a malformed URL being output by the parser. IBM researchers Justin Schuh, Tom Cross, and Peter William also reported a related symptom as pa...

Escaped null characters ignored by CSS parser — Mozilla

Kojima Hajime reported that unlike literal null characters which were handled correctly, the escaped form '\0' was ignored by the CSS parser and treated as if it was not present in the CSS input string. This issue could potentially be used to bypass script sanitization routines in web application...

-moz-binding property bypasses security checks on codebase principals — Mozilla

Security researcher Collin Jackson reported that the -moz-binding CSS property can be used to bypass security checks which validate codebase principals. Similar to the issue reported in MFSA 2008-23, Jackson demonstrated that an attacker can replace a stylesheet in a signed JAR which uses relativ...

Heap buffer overflow in external MIME bodies — Mozilla

Security research firm iDefense reported that researcher regenrecht discovered a heap-based buffer overflow vulnerability in Mozilla mail code which could potentially allow an attacker to run arbitrary code. The vulnerability is caused by allocating a buffer that can be three bytes too small in...

Auto-update compromise through DNS and SSL spoofing — Mozilla

The Firefox and Thunderbird auto-update mechanism protects itself against DNS spoofing using SSL; only a site presenting a valid certificate for aus2.mozilla.org will be trusted as a source of update information. Jon Oberheide points out, however, that many users accept unverifiable self-signed...

File stealing by changing input type (variant) — Mozilla

Chuck McAuley provided Proof-of-Concept code that demonstrates that MFSA 2006-23 was not fixed for all cases. In Firefox 1.5.0.2 it is still possible to pre-fill a text input control with the path to a file at a known location and then change the type of the input control to a file upload control...

Cross-site scripting using .valueOf.call() — Mozilla

mozbugra4 discovered that .valueOf.call and .valueOf.apply when called with no arguments were returning the Object class prototype rather than the caller's global window object. When called on a reachable property of another window this provides a hook to get around the same-origin protection,...

"AnyName" entrainment and access control hazard — Mozilla

The implementation of E4X introduced an internal "AnyName" object which was unintentionally exposed to web content. This singleton object could be used by two cooperating domains as a communication channel to get around same-origin restrictions that prevent direct access from one window or frame ...

Security Vulnerabilities fixed in Firefox for iOS 151.0 — Mozilla

Firefox for iOS hosted Reader mode on an unauthenticated local web server, allowing another application on the same device to request arbitrary URLs and receive the response rendered with the signed-in user's cookies...

Security Vulnerabilities fixed in Firefox 150 — Mozilla

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

Security Vulnerabilities fixed in Thunderbird 140.1 — Mozilla

On 64-bit platforms IonMonkey-JIT only wrote 32 bits of the 64-bit return value space on the stack. Baseline-JIT, however, read the entire 64 bits. On arm64, a WASM brtable instruction with a lot of entries could lead to the label being too far from the instruction causing truncation and incorrec...

Security Vulnerabilities fixed in Firefox ESR 115.21 — Mozilla

In resizeToAtLeast of SkRegion.cpp, there was a possible out of bounds write due to an integer overflow On Windows, a compromised content process could use bad StreamData sent over AudioIPC to trigger a use-after-free in the Browser process. This could have led to a sandbox escape. It was possibl...

Security Vulnerabilities fixed in Thunderbird 128 — Mozilla

An error in the ECMA-262 specification relating to Async Generators could have resulted in a type confusion, potentially leading to memory corruption and an exploitable crash. Clipboard code failed to check the index on an array access. This could have led to an out-of-bounds read. It was possibl...

Security Vulnerabilities fixed in Firefox for iOS 102 — Mozilla

Internal URLs are protected by a secret UUID key, which could have been leaked to web page through the Referrer header...

Partial same-origin-policy through setting location.host through data URI — Mozilla

Security researcher Armin Ebert reported that the location.host property can be set to an arbitrary string after creating an invalid data: URI. This allows for a bypass of some same-origin policy protections. This issue is mitigated by the data: URI in use and any same-origin checks for http: or...

Miscellaneous memory safety hazards (rv:43.0 / rv:38.5) — Mozilla

Mozilla developers and community identified and fixed several memory safety bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these bugs showed evidence of memory corruption under certain circumstances, and we presume that with enough effort at least some of the...

XSS attack through intents on Firefox for Android — Mozilla

Security researcher Muneaki Nishimura reported that on Firefox for Android that it is possible to create a cross-site script XSS attack through the use of Android intents and fallback navigation. This issue is caused by improper sterilization of opened addresses sent to Firefox through intents...

Memory corruption in libjar through zip files — Mozilla

Security researcher Gustavo Grieco reported a buffer underflow in libjar triggered through a maliciously crafted ZIP format file. This results in a potentially exploitable crash...

Firefox for Android addressbar can be removed after fullscreen mode — Mozilla

Security researcher Jordi Chancel reported when Firefox for Android exits fullscreen mode, it can be induce through script to not restore the addressbar when the window is redrawn in normal mode. This could allow an attacker to spoof the addressbar with their own content...

Redefinition of non-configurable JavaScript object properties — Mozilla

Security researcher André Bargull reported non-configurable properties on JavaScript objects can be redefined while parsing JSON in violation of the ECMAScript 6 standard. This allows malicious web content to bypass same-origin policy by editing these properties to arbitrary values...

Profile directory file access through file: protocol — Mozilla

Security researcher Yu Dongsong reported on Firefox for Android that a file: protocol hyperlink could link to a local file in the Firefox profile directory, bypassing access restrictions. This issue was previously addressed in Mozilla Foundation Security Advisory 2014-33 but not completely...

Bypass of XrayWrappers using XBL Scopes — Mozilla

Mozilla Developer Bobby Holley and Mozilla security researcher mozbugra4 discovered a mechanism where XBL scopes can be be used to circumvent XrayWrappers from within the Chrome on unprivileged objects. This allows web content to potentially confuse privileged code and weaken invariants and can...