CVE-2021-27922 : Vulnerability Insights and Analysis

Pillow before 8.1.1 is susceptible to a denial of service vulnerability due to improper validation of the reported size of an image container. This can lead to a significant memory allocation, causing a DoS condition.

Understanding CVE-2021-27922

This section provides insights into the impact, technical details, and mitigation strategies related to CVE-2021-27922.

What is CVE-2021-27922?

Pillow before version 8.1.1 is affected by a denial of service (DoS) vulnerability triggered by inadequate validation of image container size. Specifically, for ICNS containers, the reported size is not adequately verified, enabling potential memory allocation issues leading to memory consumption.

The Impact of CVE-2021-27922

The vulnerability in Pillow could permit an attacker to leverage this flaw to orchestrate a DoS attack by inducing extensive memory consumption through manipulated image sizes. Such attacks can exhaust system resources and impact the availability of services or systems.

Technical Details of CVE-2021-27922

Below are the key technical aspects of CVE-2021-27922.

Vulnerability Description

By exploiting the lack of proper size validation for ICNS containers in Pillow versions prior to 8.1.1, threat actors can craft malicious images with exaggerated sizes, potentially exhausting system memory upon attempted allocation.

Affected Systems and Versions

The vulnerability impacts Pillow versions before 8.1.1 that do not adequately enforce size limits for ICNS container images.

Exploitation Mechanism

Attackers can exploit this vulnerability by creating specially crafted ICNS container images with manipulated sizes, triggering excessive memory allocation attempts and resulting in a DoS condition.

Mitigation and Prevention

To address CVE-2021-27922, consider the following mitigation and prevention measures.

Immediate Steps to Take

Update Pillow to version 8.1.1 or later to mitigate the vulnerability.
Refrain from opening image files from untrusted or unknown sources.

Long-Term Security Practices

Regularly update software and libraries to the latest secure versions.
Implement robust input validation mechanisms to prevent buffer overflows and DoS attacks.

Patching and Updates

Stay informed about security advisories and promptly apply patches to enhance the resilience of your systems against potential vulnerabilities.