CVE-2026-42309
Heap Buffer Overflow in Pillow Image Processing Library
Publication date: 2026-05-09
Last updated on: 2026-05-09
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| python | pillow | From 11.2.1 (inc) to 12.2.0 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-122 | A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2026-42309 is a heap buffer overflow vulnerability in the Python Pillow imaging library affecting versions 11.2.1 to before 12.2.0.
The issue occurs when nested lists are passed as coordinates to certain Pillow APIs such as ImagePath.Path, ImageDraw.ImageDraw.polygon, and ImageDraw.ImageDraw.line. These nested lists were recursively unpacked beyond the allocated buffer size, causing a heap buffer overflow.
This vulnerability was introduced in version 11.2.1 and has been fixed in version 12.2.0 by validating that coordinate lists contain exactly two numeric coordinates.
How can this vulnerability impact me? :
This heap buffer overflow vulnerability can lead to memory corruption when processing images with Pillow using the affected functions.
Memory corruption issues like this can cause application crashes, unexpected behavior, or potentially allow an attacker to execute arbitrary code or escalate privileges depending on the context in which Pillow is used.
Since Pillow is widely used for image processing in Python applications, exploiting this vulnerability could compromise the stability and security of applications that process untrusted image data.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade the Python Pillow library to version 12.2.0 or later.
This version includes a patch that validates coordinate lists to contain exactly two numeric coordinates, preventing the heap buffer overflow caused by nested lists.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.