CVE-2026-40192
Published: 15 April 2026
Summary
CVE-2026-40192 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Python Pillow. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 38.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Computer Vision; in the Data-Related Vulnerabilities risk domain.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-40192 affects Pillow, a widely used Python imaging library, specifically versions 10.3.0 through 12.1.1. The vulnerability stems from a lack of limits on the amount of GZIP-compressed data read during the decoding of FITS images, enabling decompression bomb attacks. This flaw, classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits or Throttling), allows a specially crafted FITS file to trigger unbounded memory consumption, resulting in denial of service through out-of-memory crashes or severe performance degradation. The issue carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Attackers can exploit this vulnerability remotely without authentication or user interaction by delivering a malicious FITS file to a vulnerable Pillow installation. Any application or service processing untrusted FITS images—such as astronomical data pipelines, image viewers, or web services handling scientific imagery—is at risk. Successful exploitation leads to resource exhaustion, potentially crashing the affected process or host, though no confidentiality or integrity impacts are possible.
Pillow advisories and release notes recommend upgrading to version 12.2.0 or later, where the commit (3cb854e8b2bab43f40e342e665f9340d861aa628) and pull request (#9521) implement limits on GZIP decompression for FITS files. As a temporary workaround, users unable to upgrade immediately should restrict image processing to exclude FITS format when handling untrusted inputs. Details are available in the GitHub security advisory (GHSA-whj4-6x5x-4v2j) and Pillow 12.2.0 release notes.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23130
Vulnerability details
Pillow is a Python imaging library. Versions 10.3.0 through 12.1.1 did not limit the amount of GZIP-compressed data read when decoding a FITS image, making them vulnerable to decompression bomb attacks. A specially crafted FITS file could cause unbounded memory…
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consumption, leading to denial of service (OOM crash or severe performance degradation). If users are unable to immediately upgrade, they should only open specific image formats, excluding FITS, as a workaround.
- CWE(s)
AI Security AnalysisAI
- AI Category
- Computer Vision
- Risk Domain
- Data-Related Vulnerabilities
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: pillow
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability enables remote exploitation of image processing library for endpoint DoS via crafted FITS file causing unbounded memory consumption (application/system exploitation).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates the vulnerability by requiring timely remediation through upgrading Pillow to version 12.2.0 or later, which implements GZIP decompression limits for FITS images.
Protects against denial-of-service attacks like this decompression bomb by implementing resource controls to limit memory consumption from unbounded GZIP data in malicious FITS files.
Reduces attack surface by configuring systems to disable or restrict nonessential image processing capabilities, such as FITS format handling for untrusted inputs as a workaround.