Heap-based buffer overflow in Pillow - CVE-2026-112393

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service and potentially execute arbitrary code.

The vulnerability exists due to a heap-based buffer overflow in Pillow's _tiffWriteProc function in src/libImaging/TiffDecode.c when saving a TIFF image through libtiff to a destination without a usable file descriptor, such as io.BytesIO. A remote attacker can supply a crafted single-band TIFF with an attacker-controlled out-of-line tag value to a service that opens and re-saves the image to trigger an undersized allocation and overwrite adjacent heap memory, causing a process crash or potentially executing arbitrary code.

The reported code-execution chain additionally requires addresses disclosed by a separate vulnerability.

Affected software

How to mitigate CVE-2026-112393

External References

• https://github.com/python-pillow/Pillow/security/advisories/GHSA-332p-7hrc-92wf

Related Security Bulletins

• Multiple vulnerabilities in Pillow
• Fedora 44 update for python-pillow
• Fedora 45 update for python-pillow
• Fedora 43 update for python-pillow