{"id":113,"date":"2009-07-14T10:15:36","date_gmt":"2009-07-14T17:15:36","guid":{"rendered":"http:\/\/blog.mozilla.org\/security\/?p=113"},"modified":"2009-07-23T16:46:21","modified_gmt":"2009-07-23T23:46:21","slug":"critical-javascript-vulnerability-in-firefox-35","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/","title":{"rendered":"Critical JavaScript vulnerability in Firefox 3.5"},"content":{"rendered":"

Issue<\/strong><\/p>\n

A bug discovered last week in Firefox 3.5’s Just-in-time (JIT) JavaScript compiler was disclosed publicly<\/a> yesterday. It is a critical vulnerability that can be used to execute malicious code.<\/p>\n

Impact<\/strong><\/p>\n

The vulnerability can be exploited by an attacker who tricks a victim into viewing a malicious Web page containing the exploit code. The vulnerability can be mitigated by disabling the JIT in the JavaScript engine. To do so:<\/p>\n

    \n
  1. Enter about:config<\/code> in the browser’s location bar.<\/li>\n
  2. Type jit<\/code> in the Filter box at the top of the config editor.<\/li>\n
  3. Double-click the line containing javascript.options.jit.content<\/code> setting the value to false.<\/li>\n<\/ol>\n

    Note that disabling the JIT will result in decreased JavaScript performance and is only recommended as a temporary security measure.\u00a0 Once users have been received the security update containing the fix for this issue, they should restore the JIT setting to true by:<\/p>\n

      \n
    1. Enter about:config<\/code> in the browser’s location bar.<\/li>\n
    2. Type jit<\/code> in the Filter box at the top of the config editor.<\/li>\n
    3. Double-click the line containing javascript.options.jit.content<\/code> setting the value to true.<\/li>\n<\/ol>\n

      Alternatively, users can disable the JIT by running Firefox in Safe Mode<\/a>.\u00a0 Windows users can do so by selecting Mozilla Firefox (Safe Mode)<\/code> from the Mozilla Firefox folder.<\/p>\n

      Status<\/strong><\/p>\n

      Mozilla developers are working on a fix for this issue and a Firefox security update will be sent out as soon as the fix is completed and tested.<\/p>\n

      Credit<\/strong><\/p>\n

      Zbyte reported this issue to Mozilla and Lucas Kruijswijk helped reduce the exploit test case.<\/p>\n

      Update<\/strong>: This vulnerability has been fixed in Firefox 3.5.1<\/a>, released Thursday, July 16, 2009<\/p>\n","protected":false},"excerpt":{"rendered":"

      Issue A bug discovered last week in Firefox 3.5’s Just-in-time (JIT) JavaScript compiler was disclosed publicly yesterday. It is a critical vulnerability that can be used to execute malicious code. … Read more<\/a><\/p>\n","protected":false},"author":54,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30,69,73],"tags":[],"coauthors":[],"yoast_head":"\nCritical JavaScript vulnerability in Firefox 3.5 - Mozilla Security Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Al Billings\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/\",\"url\":\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/\",\"name\":\"Critical JavaScript vulnerability in Firefox 3.5 - Mozilla Security Blog\",\"isPartOf\":{\"@id\":\"https:\/\/blog.mozilla.org\/security\/#website\"},\"datePublished\":\"2009-07-14T17:15:36+00:00\",\"dateModified\":\"2009-07-23T23:46:21+00:00\",\"author\":{\"@id\":\"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/d33dd2d17a8109165b6df7d1245e33fc\"},\"breadcrumb\":{\"@id\":\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/blog.mozilla.org\/security\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Critical JavaScript vulnerability in Firefox 3.5\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/#website\",\"url\":\"https:\/\/blog.mozilla.org\/security\/\",\"name\":\"Mozilla Security Blog\",\"description\":\"\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/blog.mozilla.org\/security\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/d33dd2d17a8109165b6df7d1245e33fc\",\"name\":\"Al Billings\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/image\/9456a97c7c46aaacc293dfb3e668ecfd\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/59eb615338adae529ebe54960f87cd0c?s=96&d=identicon&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/59eb615338adae529ebe54960f87cd0c?s=96&d=identicon&r=g\",\"caption\":\"Al Billings\"},\"sameAs\":[\"https:\/\/openbuddha.com\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Critical JavaScript vulnerability in Firefox 3.5 - Mozilla Security Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/","twitter_misc":{"Written by":"Al Billings","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/","url":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/","name":"Critical JavaScript vulnerability in Firefox 3.5 - Mozilla Security Blog","isPartOf":{"@id":"https:\/\/blog.mozilla.org\/security\/#website"},"datePublished":"2009-07-14T17:15:36+00:00","dateModified":"2009-07-23T23:46:21+00:00","author":{"@id":"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/d33dd2d17a8109165b6df7d1245e33fc"},"breadcrumb":{"@id":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/blog.mozilla.org\/security\/2009\/07\/14\/critical-javascript-vulnerability-in-firefox-35\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/blog.mozilla.org\/security\/"},{"@type":"ListItem","position":2,"name":"Critical JavaScript vulnerability in Firefox 3.5"}]},{"@type":"WebSite","@id":"https:\/\/blog.mozilla.org\/security\/#website","url":"https:\/\/blog.mozilla.org\/security\/","name":"Mozilla Security Blog","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/blog.mozilla.org\/security\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/d33dd2d17a8109165b6df7d1245e33fc","name":"Al Billings","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/blog.mozilla.org\/security\/#\/schema\/person\/image\/9456a97c7c46aaacc293dfb3e668ecfd","url":"https:\/\/secure.gravatar.com\/avatar\/59eb615338adae529ebe54960f87cd0c?s=96&d=identicon&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/59eb615338adae529ebe54960f87cd0c?s=96&d=identicon&r=g","caption":"Al Billings"},"sameAs":["https:\/\/openbuddha.com"]}]}},"_links":{"self":[{"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/posts\/113"}],"collection":[{"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/users\/54"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/comments?post=113"}],"version-history":[{"count":0,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/posts\/113\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/media?parent=113"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/categories?post=113"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/tags?post=113"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/blog.mozilla.org\/security\/wp-json\/wp\/v2\/coauthors?post=113"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}