What is CVE-2026-34060?

CVE-2026-34060 is a high-severity code injection vulnerability in ruby-lsp (rubygems), affecting versions < 0.26.9. It is fixed in 0.26.9. Untrusted input is evaluated as executable code within the application's runtime environment.

Which versions of ruby-lsp are affected by CVE-2026-34060?

ruby-lsp (rubygems) versions < 0.26.9 is affected.

Is there a fix for CVE-2026-34060?

Yes. CVE-2026-34060 is fixed in 0.26.9. Upgrade to this version or later.

Is CVE-2026-34060 exploitable, and should I be worried?

Whether CVE-2026-34060 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.

What actually determines whether CVE-2026-34060 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.

CVE-2026-34060 in ruby-lsp

Q: Which versions of ruby-lsp are affected by CVE-2026-34060?

ruby-lsp (rubygems) versions < 0.26.9 is affected.

Q: Is there a fix for CVE-2026-34060?

Yes. CVE-2026-34060 is fixed in 0.26.9. Upgrade to this version or later.

Q: Is CVE-2026-34060 exploitable, and should I be worried?

Whether CVE-2026-34060 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.

Q: What actually determines whether CVE-2026-34060 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.

Q: How do I fix CVE-2026-34060?

Upgrade ruby-lsp to 0.26.9 or later.

Summary

Ruby LSP has arbitrary code execution through branch setting

Summary

The rubyLsp.branch VS Code workspace setting was interpolated without sanitization into a generated Gemfile, allowing arbitrary Ruby code execution when a user opens a project containing a malicious .vscode/settings.json.

Other editors that support workspace setting that get automatically applied upon opening the editor and trusting the workspace are also impacted since the server is the component that performs the interpolation.

Details

The branch CLI argument passed to the ruby-lsp server was interpolated in the generated .ruby-lsp/Gemfile without sanitization. Editors that allow defining settings saved at the workspace level (e.g.: .vscode/settings.json) that gets automatically applied open the possibility to craft a malicious repository that once opened and trusted in the editor would run arbitrary code.

Impact

Code execution with the privileges of the user who opens the malicious project. Ruby LSP assumes workspace code is trusted and so opening the editor on an untrusted workspace can lead to executing potentially dangerous code.

Remediation

The rubyLsp.branch setting has been removed entirely. VS Code extensions auto-update by default, so most users will receive the fix without action. Users who have disabled auto-updates should update to extension version >= 0.10.2.

The branch CLI flag was also entirely removed from the ruby-lsp gem. For users that don't add ruby-lsp to their Gemfiles, the server should auto-update. Users with the ruby-lsp in the Gemfile and locked to a specific version should update to >= 0.26.9.

Impact

Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.

Affected versions

ruby-lsp (< 0.26.9)

Security releases

ruby-lsp → 0.26.9 (rubygems)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade ruby-lsp to 0.26.9 or later to resolve this vulnerability.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-34060? CVE-2026-34060 is a high-severity code injection vulnerability in ruby-lsp (rubygems), affecting versions < 0.26.9. It is fixed in 0.26.9. Untrusted input is evaluated as executable code within the application's runtime environment.
Which versions of ruby-lsp are affected by CVE-2026-34060? ruby-lsp (rubygems) versions < 0.26.9 is affected.
Is there a fix for CVE-2026-34060? Yes. CVE-2026-34060 is fixed in 0.26.9. Upgrade to this version or later.
Is CVE-2026-34060 exploitable, and should I be worried? Whether CVE-2026-34060 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
What actually determines whether CVE-2026-34060 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.
How do I fix CVE-2026-34060? Upgrade ruby-lsp to 0.26.9 or later.