CVE-2023-50447 in Pillow
Summary
by MITRE • 01/19/2024
Pillow through 10.1.0 allows PIL.ImageMath.eval Arbitrary Code Execution via the environment parameter, a different vulnerability than CVE-2022-22817 (which was about the expression parameter).
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Analysis
by VulDB Data Team • 03/31/2026
The vulnerability identified as CVE-2023-50447 affects the Pillow library version 10.1.0 and earlier, representing a critical arbitrary code execution flaw that specifically targets the environment parameter within PIL.ImageMath.eval functionality. This vulnerability operates under CWE-94 which categorizes improper control of generation of code, making it particularly dangerous as it allows attackers to execute arbitrary commands on systems running vulnerable versions of the library. The flaw differs significantly from CVE-2022-22817 which targeted the expression parameter, demonstrating that multiple attack vectors exist within the same library function. The environment parameter in PIL.ImageMath.eval is designed to provide additional context variables for image mathematical operations but becomes a critical security weakness when improperly validated.
The technical exploitation of this vulnerability occurs when an attacker can manipulate the environment parameter passed to PIL.ImageMath.eval function. This parameter accepts dictionary-like objects that are processed within the evaluation context, allowing malicious input to be interpreted as executable code rather than simple variable references. Attackers can craft environment dictionaries containing crafted Python expressions that bypass normal input validation, leading to code execution on the target system with the privileges of the process running the Pillow library. The vulnerability is particularly concerning because it leverages legitimate library functionality to achieve unauthorized code execution, making detection more challenging and the attack surface broader than typical injection flaws.
Operationally, this vulnerability poses significant risks to web applications, image processing services, and any systems that utilize Pillow for image manipulation tasks. The impact extends beyond simple code execution to potential privilege escalation and system compromise, as attackers can leverage this flaw to gain unauthorized access to sensitive data or execute malicious payloads. Systems processing user-uploaded images or performing automated image transformations become prime targets for exploitation, particularly in environments where the library runs with elevated privileges. The vulnerability affects various deployment scenarios including cloud services, content management systems, and image processing pipelines that rely on Pillow for their functionality.
Mitigation strategies for CVE-2023-50447 primarily involve immediate upgrading to Pillow version 10.1.1 or later, which includes patches addressing the environment parameter validation issue. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additional protective measures include input validation at application level, sandboxing image processing operations, and implementing strict access controls around image processing functionality. Security teams should also consider monitoring for suspicious image processing activities and implementing network segmentation to limit potential lateral movement if exploitation occurs. The vulnerability's classification under ATT&CK technique T1059.007 for command and scripting interpreter provides guidance for threat detection and response activities, emphasizing the need for monitoring code execution patterns within image processing contexts.