Some vulnerabilities have been reported in libpng, which can be exploited by malicious people to cause a DoS (Denial of Service).

1) Certain errors within libpng, including a logical NOT instead of a bitwise NOT in pngtrtran.c, an error in the 16bit cheap transparency extension, and an incorrect use of sizeof() may be exploited to crash an application using the library.

2) Various out-of-bounds read errors exist within the functions "png_handle_pCAL()", "png_handle_sCAL()", "png_push_read_tEXt()", "png_handle_iTXt()", and "png_handle_ztXt()", which may be exploited by exploited to crash an application using the library.

The vulnerabilities are reported in versions prior to 1.2.21.

Solution
Update to version 1.2.21.

Provided and/or discovered by
1) George Cook and Jeff Phillips
2) Tavis Ormandy

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://www.libpng.org/pub/png/libpng.html
http://sourceforge.net/mailarchive/forum.php?thread_name=3.0.6.32.20071004082318.012a7628%40mail.comcast.net&forum_name=png-mng-implement

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