CVE-2026-26189: Trivy Action has a script injection via sourced env file in composite action

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 trivyenvs.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 trivyenvs.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:

yaml - uses: aquasecurity/trivy-action@0.33.1 with: output: "trivy-${{ github.event.pullrequest.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 ./trivyenvs.txt pattern Workflows where user input is not accessible.

Call Sites:

action.yaml:188 — setenvvarifprovided writes unescaped export lines entrypoint.sh:9 — sources ./trivyenvs.txt