When PHP EXIF extension is parsing EXIF information from an image, e.g. via exif_read_data() function, in PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13 and 7.4.0 it is possible to supply it with data what will cause it to read past the allocated buffer. This may lead to information disclosure or crash.
Created php tracking bugs for this issue:
Affects: fedora-all [bug 1788259]
Upstream commit for this issue: http://git.php.net/?p=php-src.git;a=commit;h=c14eb8de974fc8a4d74f3515424c293bc7a40fba
There's an issue with EXIF module in PHP when exif tries to read maker notes from a given image metadata. When iterating on exif directories on exif_process_IFD_in_MAKERNOTE() starts to walk the buffer by the offset read but it doesn't decrement the remaining length of the buffer by the same proportion. An attack may leverage this issue by crafting an image with a malicious EXIF information, leading to Confidentiality impact and eventually DoS.
Both confidentiality and availability impact may be considered low. The attack has access just to a small amount of bytes from process heap and only a the single execution for this is affected.