🛡️ CVE-2026-34060 — ruby-lsp

🔴 CVSS 9.8 — Critical ✅ No Known Exploit CWE-94 NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-34060 is classified as CWE-94: Code Injection. Input is incorporated into code that the runtime evaluates, so an attacker can have their own code executed.

Affected software

CVE-2026-34060 is recorded against 2 packages.

  • ruby-lsp (fixed in 0.26.9)
  • unknown

Timeline and source

Published on 27 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)
github.com (Web)
github.com (Web)

CVE-2026-34060 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-94
Public Exploit ✅ No
Source NVD
Published 2026-03-27
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
ruby-lsp — 0.26.9
unknown — —

Similar Threats

Exploit Protection

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