CVE-2026-26189

Command Injection in aquasecurity/trivy-action via Unsanitized Environment Variable Export

A command injection vulnerability exists in aquasecurity/trivy-action due to improper handling of action inputs when exporting environment variables. The action writes export VAR=<input> lines to trivy_envs.txt based on user-supplied inputs and subsequently sources this file in entrypoint.sh.

Because input values are written without appropriate shell escaping, attacker-controlled input containing shell metacharacters (e.g., $(...), backticks, or other command substitution syntax) may be evaluated during the sourcing process. This can result in arbitrary command execution within the GitHub Actions runner context.

Severity:

Moderate

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N

CWE-78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)

Impact:

Successful exploitation may lead to arbitrary command execution in the CI runner environment.

Affected Versions:

• Versions >= 0.31.0 and <= 0.33.1
• Introduced in commit 7aca5ac

Affected Conditions:

The vulnerability is exploitable when a consuming workflow passes attacker-controlled data into any action input that is written to trivy_envs.txt. Access to user input is required by the malicious actor.

A representative exploitation pattern involves incorporating untrusted pull request metadata into an action parameter. For example:

- uses: aquasecurity/[email protected]
  with:
    output: "trivy-${{ github.event.pull_request.title }}.sarif"

If the pull request title contains shell syntax, it may be executed when the generated environment file is sourced.

Not Affected:

• Workflows that do not pass attacker-controlled data into trivy-action inputs
• Workflows that upgrade to a patched version that properly escapes shell values or eliminates the source ./trivy_envs.txt pattern
• Workflows where user input is not accessible.

Call Sites:

• action.yaml:188, set_env_var_if_provided writes unescaped export lines
• entrypoint.sh:9, sources ./trivy_envs.txt

Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.

CVE-2026-26189 has a CVSS score of 5.9 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.34.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-26189? CVE-2026-26189 is a medium-severity OS command injection vulnerability in aquasecurity/trivy-action (actions), affecting versions >= 0.31.0, < 0.34.0. It is fixed in 0.34.0. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
2. How severe is CVE-2026-26189? CVE-2026-26189 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of aquasecurity/trivy-action are affected by CVE-2026-26189? aquasecurity/trivy-action (actions) versions >= 0.31.0, < 0.34.0 is affected.
4. Is there a fix for CVE-2026-26189? Yes. CVE-2026-26189 is fixed in 0.34.0. Upgrade to this version or later.
5. Is CVE-2026-26189 exploitable, and should I be worried? Whether CVE-2026-26189 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-26189 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-26189? Upgrade aquasecurity/trivy-action to 0.34.0 or later.