CVE-2026-59831: GitHub CLI `gh codespace jupyter` could allow remote code execution when connecting to a malicious Codespace

Severity: medium (CVSS 4.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-09 · updated 2026-07-14
Weakness: CWE-829

Description

GitHub CLI (gh) is GitHub’s official command line tool. From 2.10.0 through 2.95.0, connecting to a malicious Codespace with gh codespace jupyter can allow command execution because the command opens a JupyterLab URL supplied by a process inside the Codespace without validating that it is a loopback HTTP or HTTPS address, allowing a crafted vscode:// or vscode-insiders:// URL to be handed to VS Code. This issue is fixed in version 2.96.0.

Affected products

cli: from 2.10.0, < 2.96.0

References

https://github.com/cli/cli/commit/b300f2ec7ec9dc9addc39b2ad88c54097ded7ca0
https://github.com/cli/cli/releases/tag/v2.96.0
https://github.com/cli/cli/security/advisories/GHSA-8cg3-r6g9-fpg2

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