CVE-2026-26189 is a medium-severity (CVSS 5.9) OS Command Injection vulnerability in aquasecurity/trivy-action. A fix is available for aquasecurity/trivy-action — see the affected versions and patch details below.
Trivy Action has a script injection via sourced env file in composite action
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-26189.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-26189 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
aquasecurity/trivy-actionReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects GitHub Actions packages — download data is not available via public APIs for these ecosystems.
Description
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-actioninputs - Workflows that upgrade to a patched version that properly escapes shell values or eliminates the
source ./trivy_envs.txtpattern - Workflows where user input is not accessible.
Call Sites:
action.yaml:188—set_env_var_if_providedwrites unescapedexportlinesentrypoint.sh:9— sources./trivy_envs.txt
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦GitHub Actions | aquasecurity/trivy-action | ≥ 0.31.0&&< 0.34.0 | 0.34.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for aquasecurity/trivy-action, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update aquasecurity/trivy-action to 0.34.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26189 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-26189 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-26189. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-26189 in your dependencies?
O3 Security finds CVE-2026-26189 across GitHub Actions dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.