Mozilla released a critical update on Tuesday, fixing seven security flaws in its Firefox browser. These fixes are all included in the Firefox 13 browser release.

Firefox 13 should download automatically for most users and be installed once the browser is shut down. Several severe fixes are addressed in this version, including a pair of critical buffer overflows and some use after free vulnerabilities. A google reseacher was responsible for finding the flaws.

"The first heap buffer overflow was found in conversion from unicode to native character sets when the function fails. The use-after-free occurs in nsFrameList when working with column layout with absolute positioning in a container that changes size. The second buffer overflow occurs in nsHTMLReflowState when a window is resized on a page with nested columns and a combination of absolute and relative positioning. All three of these issues are potentially exploitable," the Mozilla advisory says.

Several memory-safety problems were also discovered by Mozilla engineers and were fixed in the latest version.

"Mozilla developers 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 these could be exploited to run arbitrary code," Mozilla said in the Firefox advisory.

"In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products."

Firefox users should update their browsers as soon as possible to protect themselves against these bugs. You can get it HERE on MajorGeeks.com