Authenticated command execution via workflow input interpolation
Published Apr 21, 2026 · Updated Apr 21, 2026
Command injection in Lawnchair before commit fcba413 allows remote authenticated users to execute commands on a GitHub Actions runner. The Release Update workflow embeds the artifactName dispatch input directly into a shell run expression, so shell metacharacters are parsed as commands. Repository access sufficient to dispatch that workflow is required; successful exploitation runs in the workflow runner context and exposes its secrets and credentials.
Summary
What happened
Command injection in Lawnchair before commit fcba413 allows remote authenticated users to execute commands on a GitHub Actions runner. The Release Update workflow embeds the artifactName dispatch input directly into a shell run expression, so shell metacharacters are parsed as commands. Repository access sufficient to dispatch that workflow is required; successful exploitation runs in the workflow runner context and exposes its secrets and credentials.
The record
- CVE
- CVE-2026-39866
- Published
- Apr 21, 2026
- Updated
- Apr 21, 2026
- Vendor
- LawnchairLauncher
- Product
- Lawnchair
- Classifications
- CWE-77, T1059
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 21, 2026CVE publishedPublication date reported by the CVE source.
- Apr 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< fcba413f55dd47f8a3921445252849126c6266b2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Workflow dispatch artifactName command-injection PoCproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo