The ReadMNGImage function in coders/png.c in GraphicsMagick 1.3.26 has an out-of-order CloseBlob call, resulting in a use-after-free via a crafted file.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
| Link | Tags |
|---|---|
| https://www.debian.org/security/2018/dsa-4321 | vendor advisory |
| https://blogs.gentoo.org/ago/2017/07/12/graphicsmagick-use-after-free-in-closeblob-blob-c/ | vdb entry third party advisory patch |
| https://lists.debian.org/debian-lts-announce/2018/08/msg00002.html | mailing list |
| http://hg.code.sf.net/p/graphicsmagick/code/rev/d0a76868ca37 | issue tracking third party advisory patch |
| https://usn.ubuntu.com/4206-1/ | vendor advisory |