How severe is GHSA-c4r5-fxqw-vh93?

No CVSS score has been assigned to GHSA-c4r5-fxqw-vh93 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-c4r5-fxqw-vh93?

GHSA-c4r5-fxqw-vh93 affects the following packages: ruby-lsp (RubyGems). Ecosystems affected: RubyGems.

How do I fix GHSA-c4r5-fxqw-vh93?

Update ruby-lsp to 0.26.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c4r5-fxqw-vh93 is resolved across your whole dependency graph.

How do I detect GHSA-c4r5-fxqw-vh93 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ruby-lsp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-c4r5-fxqw-vh93 if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-c4r5-fxqw-vh93?

O3 pinpoints whether GHSA-c4r5-fxqw-vh93 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-c4r5-fxqw-vh93 actively exploited in the wild?

No public exploit code has been indexed for GHSA-c4r5-fxqw-vh93 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-c4r5-fxqw-vh93?

GHSA-c4r5-fxqw-vh93 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 37th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-c4r5-fxqw-vh93?

GHSA-c4r5-fxqw-vh93 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-c4r5-fxqw-vh93 published, and has it been updated?

GHSA-c4r5-fxqw-vh93 was published on March 27, 2026 and was last updated on March 31, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

GHSA-c4r5-fxqw-vh93

Ruby LSP has arbitrary code execution through branch setting

Also known asCVE-2026-34060

Published

Mar 27, 2026

Updated

Mar 31, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk37th percentile+0.45%

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.

Blast Radius

1 pkg affected

💎ruby-lsp

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`ruby-lsp`	all versions	0.26.9

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ruby-lsp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update ruby-lsp to 0.26.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c4r5-fxqw-vh93 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 pinpoints whether GHSA-c4r5-fxqw-vh93 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-c4r5-fxqw-vh93. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

**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.

O3 Security · Impact-Aware SCA

Is GHSA-c4r5-fxqw-vh93 in your dependencies?

O3 detects GHSA-c4r5-fxqw-vh93 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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