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Mozilla Patches Critical Vulnerabilities With Release of Firefox 37

Firefox 37, the latest version of Mozilla’s web browser, includes fixes for over a dozen security issues, including several vulnerabilities that have been rated critical.

A security researcher known as Nils has identified and reported two type confusion vulnerabilities (CVE-2015-0803, CVE-2015-0804) that can lead to use-after-free errors and exploitable crashes.

“The first of these occurs while setting specific attributes of a source element resulting in incorrect object casting. The second flaw occurs when binding a source to a tree when the function fails to validate the namespace,” Mozilla said in an advisory.

Abhishek Arya of the Google Chrome Security Team discovered two potentially exploitable memory corruption crashes during 2D rendering (CVE-2015-0805, CVE-2015-0806).

Another serious vulnerability was identified by Aki Helin. The researcher found a use-after-free flaw that occurs when playing certain MP3 files using the Fluendo plugin for the GStreamer multimedia framework (CVE-2015-0813). The bug, which is caused by the way the plugin handles certain MP3 files and the way it interacts with Mozilla code, affects only Linux installations.

Various memory safety problems and crashes discovered by Mozilla developers have also been rated as critical (CVE-2015-0814, CVE-2015-0815).

Last week, Mozilla released security updates for Firefox 36 to address the vulnerabilities disclosed by researchers at the Pwn2Own 2015 hacking contest. One of the bugs was a privilege escalation reported by Mariusz Mlynski. Mozilla developers identified a different variant of the vulnerability found by Mlynski (CVE-2015-0801).

“The previously reported flaw used an issue with SVG content navigation to bypass same-origin policy protections to run scripts in a privileged context. This newer variant found that the same flaw could be used during anchor navigation of a page, allowing bypassing of same-origin policy protections,” Mozilla said.

This isn’t the only vulnerability discovered during the investigation of a previously reported issue. Mozilla developer Christoph Kerschbaumer (CVE-2015-0807) found a high severity flaw that could be exploited for cross-site request forgery (CSRF) attacks while analyzing a bug reported by Muneaki Nishimura in January.

The list of moderate severity vulnerabilities patched with the release of Firefox 37 includes an out-of-bounds read in the QCMS library, a privilege escalation caused by the fact that windows can retain access to privileged content, a cursor clickjacking bug (only affects OS X), and an approval bypass when installing a Firefox lightweight theme.

At Pwn2Own 2015, Mlynski also demonstrated that documents loaded through a “resource:” URL could load privileged pages. This vulnerability, rated moderate, has been resolved in Firefox 37.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.