Executive brief
libtiff is a widely-used library for reading and writing TIFF image files, integrated into many document processing, photo editing, and imaging applications. An integer overflow vulnerability in the thumbnail.c component allows an attacker to trigger an out-of-bounds memory write by crafting a malicious TIFF file, potentially leading to arbitrary code execution when the thumbnail tool processes the file.
Technical details
The vulnerability is an integer overflow in the thumbnail buffer allocation logic within libtiff/tools/thumbnail.c:main(). The vulnerable code calculates thumbnail buffer size by multiplying thumbnail width (tnw) and height (tnh) without proper overflow checking; an attacker can supply crafted dimensions that cause the multiplication to overflow, resulting in a small buffer allocation. Subsequent write operations then overflow the allocated buffer. The attack vector is network-reachable (via malicious TIFF files) and requires no authentication; the attacker must convince a user or automated system to process a specially crafted TIFF image. The fix, implemented in commit 9ce4d089, uses _TIFFMultiply32() with overflow detection before allocation. A patch is available in the libtiff repository.
Affected products
- libtiff libtiff prior to commit 9ce4d089bcf25496663776d9e6336738112f09a3
Timeline
- 2026-08-25: disclosed
- 2026-03-03: patched: Fix committed as 9ce4d089bcf25496663776d9e6336738112f09a3