CVE-2025-68119 is an OS command injection vulnerability classified under CWE-78, affecting the Go toolchain's cmd/go module downloader in version 1.25.0. The vulnerability is triggered when the toolchain processes maliciously crafted version strings during module download and build operations. Specifically, on systems where Mercurial (hg) is installed, the vulnerability arises from improper neutralization of special elements in external VCS command construction, allowing an attacker to execute arbitrary local code. On systems with Git installed, the vulnerability allows an attacker to write arbitrary files to the filesystem by exploiting the way version strings are handled. The attack vector requires the attacker to supply malicious version strings explicitly; normal usage patterns such as using @latest or bare module paths are not vulnerable. The CVSS v3.1 score is 7.0 (high), reflecting local attack vector, high attack complexity, low privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. No public exploits are currently known. The vulnerability highlights the risk of trusting unvalidated version strings in module management tools and the dangers of command injection when external VCS commands are constructed unsafely. This issue is particularly relevant for development environments that rely on custom or non-standard module sources and have Mercurial or Git installed.

For European organizations, this vulnerability poses a significant risk to software development environments using Go 1.25.0, especially those that incorporate modules from non-standard or custom sources. Successful exploitation can lead to local code execution or arbitrary file writes, potentially compromising developer workstations or build servers. This can result in unauthorized code execution, data tampering, or disruption of build processes, undermining software integrity and availability. Given the reliance on Go in many European tech companies, fintech, and critical infrastructure software development, the impact could extend to supply chain security and downstream applications. Organizations with lax controls on module version inputs or that allow developers to specify arbitrary versions without validation are particularly vulnerable. The requirement for local access and explicit malicious version strings somewhat limits remote exploitation but does not eliminate insider threats or attacks via compromised developer machines. The absence of known exploits suggests a window for proactive mitigation before widespread abuse.

European organizations should implement strict validation and sanitization of version strings used in Go module downloads, especially when sourcing from non-standard or custom domains. Avoid using untrusted or arbitrary version strings and restrict module downloads to trusted repositories. Upgrade to patched versions of the Go toolchain as soon as they become available. In the interim, consider disabling or limiting the use of Mercurial and Git in build environments if not required or isolate build environments to reduce risk. Employ least privilege principles for developer and build system accounts to minimize the impact of local code execution. Monitor build logs and filesystem changes for unusual activity related to module downloads. Incorporate static and dynamic analysis tools to detect suspicious command constructions or file writes during builds. Educate developers about the risks of using unverified module versions and enforce policies that prevent arbitrary version string inputs. Finally, maintain up-to-date inventories of development tools and dependencies to quickly identify affected systems.