CVE-2026-114501 Pillow: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1

What is CVE-2026-114501?

CVE-2026-114501 is a medium-severity vulnerability in Python Pillow, published on 21 Oct 2026.

Official description

Pillow is a Python imaging library. From 11.2.1 until 13.0.0, Arrow export assumes that an image's rows are tightly contiguous and exports from im->blocks[0].ptr even when PILLOW_ALIGNMENT makes aligned_linesize include row padding or an aligned offset before the first row. The resulting Arrow buffer can include uninitialized padding, bytes preceding the first row, or stale heap contents from previously freed images. Applications that configure alignment and export images to Arrow can therefore disclose one user's pixels or other process memory to another user. This issue is fixed in version 13.0.0.

Weakness: CWE-908, CWE-226

Which versions are affected by CVE-2026-114501?

4 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.

Products include Python Pillow.

How do I fix CVE-2026-114501?

Upgrade pillow to 13.0.0 or later.

Is CVE-2026-114501 being exploited?

There is no known exploitation of CVE-2026-114501 in the wild and no public exploit code.

Other vulnerabilities in Python Pillow

• CVE-2014-3007 Pillow command injection Critical 10.0
• CVE-2026-96639 Pillow multi-frame loaders can reuse stale native image storage after mode transitions Critical 9.8
• CVE-2022-30595 Buffer over-flow in Pillow Critical 9.8
• CVE-2021-25289 Out of bounds write in Pillow Critical 9.8
• CVE-2016-4009 Pillow Integer overflow in ImagingResampleHorizontal Critical 9.8

All Python Pillow vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-pillow-2026-114501, CLSA-2026-1793101237, DEBIAN-CVE-2026-114501, ECHO-260c-4537-5719, GHSA-654x-cwwv-5j9c, PYSEC-2026-4336 and 1 more.