CVE-2021-33629 in isula-build
Summary
by MITRE • 07/26/2021
isula-build before 0.9.5-8 can cause a program crash, when building container images, some functions for processing external data do not remove spaces when processing data.
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Analysis
by VulDB Data Team • 08/05/2021
The vulnerability identified as CVE-2021-33629 affects isula-build versions prior to 0.9.5-8, representing a critical input validation flaw that can lead to denial of service conditions during container image construction processes. This issue stems from inadequate data sanitization practices within the build tool's external data processing functions, where whitespace characters are not properly stripped or handled during data ingestion. The vulnerability manifests specifically when the build system encounters malformed or improperly formatted input data, causing the program to crash and terminate unexpectedly. Such behavior creates operational disruptions for developers and DevOps teams relying on automated container building workflows, potentially leading to failed deployments and extended downtime in production environments.
The technical root cause of this vulnerability aligns with CWE-20, which addresses improper input validation, and CWE-704, concerning incorrect type conversion or handling. The flaw represents a classic buffer manipulation issue where external data inputs containing trailing or leading whitespace characters are not normalized before processing, leading to unpredictable behavior in the parsing functions. When isula-build attempts to process these unfiltered inputs, the absence of proper whitespace removal causes parsing failures that ultimately result in segmentation faults or similar runtime exceptions. This vulnerability operates at the application layer and can be exploited through crafted input data that triggers the specific processing paths where whitespace handling is inadequate, making it particularly dangerous in automated build environments where inputs may come from untrusted sources or be subject to manipulation.
The operational impact of CVE-2021-33629 extends beyond simple program termination, as it can disrupt entire CI/CD pipelines and automated deployment workflows that depend on isula-build for container image creation. Attackers could potentially leverage this vulnerability to perform denial of service attacks against build servers by submitting maliciously formatted data that triggers the crash condition. In enterprise environments where containerized applications are routinely built and deployed, this vulnerability could enable adversaries to cause service interruptions and disrupt development cycles. The vulnerability also presents a risk in environments where build systems process data from multiple sources, as a single malformed input could compromise the entire build process and potentially affect downstream dependent systems. Organizations utilizing isula-build for container orchestration may experience cascading failures if build processes are interrupted, leading to extended deployment delays and increased operational overhead.
Mitigation strategies for CVE-2021-33629 should prioritize immediate patching of affected isula-build installations to version 0.9.5-8 or later, which contains the necessary fixes for proper whitespace handling in external data processing functions. Organizations should implement additional input sanitization measures at the application level, ensuring that all external data is normalized before being processed by build tools. Network-level defenses should include monitoring for unusual patterns in build system activity that might indicate exploitation attempts, while also implementing proper access controls to limit who can submit data to build processes. The ATT&CK framework's technique T1499.004, which covers network denial of service, could be relevant in understanding how this vulnerability might be exploited in broader attack scenarios. Regular security assessments of container build environments should be conducted to identify similar input validation weaknesses in other tools and processes, while implementing automated testing procedures that include malformed input validation to prevent similar issues from emerging in future releases.