The vulnerability CVE-2026-25063 affects gradle-completion, a tool providing Bash and Zsh command-line completion support for Gradle builds. Specifically, versions prior to 9.3.1 contain a command injection flaw in the Bash completion script. When a user triggers tab completion in Bash within a Gradle project, the script enumerates Gradle tasks and their descriptions to present completion options. However, the script fails to properly sanitize task names and descriptions, particularly those containing strings enclosed in backticks (`). In Bash, backticks denote command substitution, so any command embedded within backticks in a task description is executed by the shell during completion. This allows an attacker who can inject a malicious Gradle build file with crafted task descriptions to execute arbitrary OS commands on the victim’s machine when the victim uses Bash tab completion. The vulnerability does not require explicit task execution, only the invocation of tab completion, which is a common developer action. The flaw does not affect Zsh completion, which properly handles such input. Exploitation requires local access and user interaction (triggering tab completion) and assumes the user has privileges to run Gradle commands. The vulnerability impacts confidentiality, integrity, and availability since arbitrary code execution can lead to data theft, system compromise, or denial of service. The issue was patched in gradle-completion version 9.3.1. As an interim mitigation, disabling Bash completion for Gradle by removing the gradle-completion script from shell initialization files (.bashrc or .bash_profile) prevents exploitation. No known active exploits have been reported in the wild to date.

For European organizations, this vulnerability primarily threatens development environments where Gradle is used with Bash shells. Successful exploitation can lead to arbitrary code execution with the privileges of the user running Bash, potentially compromising developer workstations or build servers. This can result in theft of sensitive source code, insertion of malicious code into builds, or disruption of development pipelines. Organizations relying on continuous integration systems or automated builds using Gradle with Bash completion enabled may face elevated risk. The vulnerability could also be leveraged for lateral movement within internal networks if attackers gain initial access. Confidentiality is at risk due to potential data exfiltration, integrity is compromised by unauthorized code execution, and availability may be affected by destructive payloads. The requirement for local user interaction and privileges limits remote exploitation but insider threats or social engineering could facilitate attacks. The lack of impact on Zsh users reduces the attack surface somewhat. Overall, the vulnerability poses a significant risk to European software development and build environments that have not updated to the patched version or applied mitigations.

1. Upgrade gradle-completion to version 9.3.1 or later immediately to apply the official patch that properly sanitizes task names and descriptions. 2. As a temporary workaround, disable Bash completion for Gradle by removing or commenting out the gradle-completion script invocation in user shell initialization files such as .bashrc or .bash_profile. 3. Educate developers and build engineers about the risk of opening projects with untrusted or unknown Gradle build files, especially when using Bash tab completion. 4. Implement strict code review and repository access controls to prevent malicious Gradle build files from entering trusted codebases. 5. Monitor developer workstations and build servers for unusual command execution or process activity that could indicate exploitation attempts. 6. Encourage use of Zsh or other shells not affected by this vulnerability as an interim mitigation. 7. Restrict local user privileges where possible to limit the impact of arbitrary code execution. 8. Integrate vulnerability scanning and dependency checks into CI/CD pipelines to detect outdated gradle-completion versions. 9. Maintain updated backups of critical development environments to enable recovery in case of compromise.