python-pillow Pillow Out-Of-Bounds Read Flaw (CVE-2026-96639) Rated CVSS 9.8
A newly published critical vulnerability in python-pillow Pillow carries a CVSS score of 9.8. Here is what is affected and how to respond.
Key points
- CVE-2026-96639 affects python-pillow Pillow.
- CVSS 9.8 (Critical).
- No exploitation confirmed yet.
python-pillow Pillow is affected by CVE-2026-96639, a out-of-bounds read that the National Vulnerability Database rates 9.8 out of 10.
At a glance
- CVE
- CVE-2026-96639
- Product
- python-pillow Pillow
- CVSS
- 9.8 Critical
- Weakness
- out-of-bounds read
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| Python-Pillow | Pillow | >= 11.0.0, < 13.0.0 |
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-96639
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-96639?
CVE-2026-96639 is a out-of-bounds read vulnerability in python-pillow Pillow.
How severe is CVE-2026-96639?
It has a CVSS score of 9.8 Critical.
Is CVE-2026-96639 being exploited?
There is no public confirmation of exploitation at the time of publication.
