CVE-2026-112399: CWE-789: Memory Allocation with Excessive Size Value in python-pillow Pillow
Description
A high-severity vulnerability in the Python Pillow imaging library allows memory exhaustion via crafted APNG images. Versions from 8.1.0 up to but not including 13.0.0 are affected. The flaw involves allocating a large memory buffer for an APNG disposal background before performing decompression-bomb checks, enabling denial of service. This issue is fixed in version 13.0.0.
CVSS v4.0
Score 8.7high
Affected software
python-pillow
Pillow
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Pillow versions 8.1.0 through 12.x allocate an APNG disposal background at the full canvas size before applying decompression-bomb checks during image opening. A specially crafted APNG with a small first frame but a very large declared canvas size and specific disposal or frame operations triggers the allocation inside Image.open() without loading pixels or iterating frames. This can exhaust system memory and cause a denial of service. The vulnerability is identified as CWE-789 (Memory Allocation with Excessive Size Value) and is addressed in Pillow 13.0.0.
Potential Impact
An attacker can cause the Pillow library to allocate excessive memory when processing a malicious APNG image, leading to memory exhaustion and denial of service. This occurs without requiring user interaction or privileges and can disrupt applications relying on Pillow for image processing.
Mitigation Recommendations
Upgrade to Pillow version 13.0.0 or later, where this issue is fixed. No other mitigations are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-19T16:58:51.959Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad68cd42cdf04f65692eebf
Added to database: 10/19/2026, 21:34:12 UTC
Last enriched: 10/19/2026, 21:48:21 UTC
Last updated: 10/19/2026, 21:48:21 UTC
Views: 3
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