# CVE-2026-52491: libtiff integer overflow in thumbnail buffer allocation

Source: https://junglewise.ai/threats/cve-2026-52491-libtiff-integer-overflow-in-thumbnail-buffer-allocation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-25. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-52491 · Severity: high · CVSS 8.4 · Published 2026-08-25

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.

Technologies: [Libtiff](https://junglewise.ai/threats/technologies/libtiff). Vendors: [Libtiff](https://junglewise.ai/threats/vendors/libtiff).

## Quick answers

**Is CVE-2026-52491 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52491 being exploited in the wild.

**How severe is CVE-2026-52491?** High severity, with a CVSS score of 8.4, published 25 August 2026.

**Which products and versions are affected?** Libtiff prior to commit 9ce4d089bcf25496663776d9e6336738112f09a3.

**Is there a fix for CVE-2026-52491?** A patch was published on 2026-03-03: Fix committed as 9ce4d089bcf25496663776d9e6336738112f09a3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-52491 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-52491?** Check whether you run Libtiff at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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

## References

- [https://gist.github.com/okyfh/5cc53fa67d229017231cf18c91768bd9](https://gist.github.com/okyfh/5cc53fa67d229017231cf18c91768bd9)
- [https://gitlab.com/libtiff/libtiff/-/commit/9ce4d089bcf25496663776d9e6336738112f09a3](https://gitlab.com/libtiff/libtiff/-/commit/9ce4d089bcf25496663776d9e6336738112f09a3)

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