CVE-2023-29402 in cmd-go
Summary
by MITRE • 06/09/2023
The go command may generate unexpected code at build time when using cgo. This may result in unexpected behavior when running a go program which uses cgo. This may occur when running an untrusted module which contains directories with newline characters in their names. Modules which are retrieved using the go command, i.e. via "go get", are not affected (modules retrieved using GOPATH-mode, i.e. GO111MODULE=off, may be affected).
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability identified as CVE-2023-29402 represents a critical security flaw in the go command's handling of cgo functionality, specifically when processing modules containing directory names with newline characters. This issue stems from the Go programming language's build system and its interaction with the cgo toolchain that enables Go programs to call C code. The vulnerability manifests when the go command processes untrusted modules that contain directories with embedded newline characters in their names, creating a path traversal scenario that can lead to unexpected code generation during the build process. This behavior deviates from the expected deterministic compilation process that Go developers rely upon for security and predictability.
The technical root cause of this vulnerability lies in how the go command parses and handles directory names during module retrieval and processing. When encountering modules with newline characters in directory names, the parsing logic fails to properly sanitize these inputs, allowing maliciously crafted module structures to influence the build process. This flaw operates at the intersection of path handling and code generation, where the cgo toolchain interprets the malformed directory names as legitimate path components, potentially leading to the inclusion of unintended code or the execution of unexpected build operations. The vulnerability is particularly dangerous because it can be exploited through untrusted modules retrieved via the go get command, which is a common practice in Go development environments.
The operational impact of CVE-2023-29402 extends beyond simple code generation anomalies to potentially enable arbitrary code execution or privilege escalation within the build environment. When developers or automated systems process untrusted modules containing these specially crafted directory names, the resulting build artifacts may contain unexpected behavior that could compromise system integrity. This vulnerability affects the fundamental security model of Go applications, as it undermines the trust assumptions developers make when using external modules. The risk is particularly elevated in continuous integration environments where automated module retrieval and build processes are common, as these systems may unknowingly incorporate maliciously constructed modules that exploit this vulnerability to inject harmful code into the build pipeline.
Organizations and developers should implement immediate mitigations to address this vulnerability, including updating to Go versions that contain the relevant fixes and implementing strict module validation processes. The recommended approach involves ensuring that all module retrieval operations occur in module mode (GO111MODULE=on) rather than GOPATH mode, as the latter is more susceptible to this vulnerability. Additionally, organizations should establish policies for vetting external modules and implementing sandboxed build environments that limit the potential impact of malicious code generation. Security teams should monitor their Go-based applications for signs of exploitation and consider implementing runtime monitoring to detect anomalous code behavior that might indicate successful exploitation of this vulnerability.
This vulnerability aligns with CWE-22 Path Traversal and CWE-78 Command Injection categories, reflecting the fundamental security issues in input validation and path handling within the Go toolchain. From an ATT&CK perspective, this vulnerability maps to T1133 External Remote Services and T1059 Command and Scripting Interpreter, as it enables adversaries to manipulate build processes through external module dependencies. The vulnerability demonstrates the importance of input sanitization in build systems and highlights the need for comprehensive security testing of development toolchains. Organizations should treat this as a high-priority vulnerability requiring immediate attention, particularly in environments where untrusted code is regularly processed or where automated build systems are prevalent.