CVE-2026-111058: Mercury: Unauthenticated Remote Code Execution via /api/kernels

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-19 · updated 2026-10-19
Weakness: CWE-862

Description

Mercury is a Python framework for sharing Jupyter notebooks as web applications and dashboards. Prior to 3.2.6, default tokenless deployments allow anonymous clients to create Jupyter kernels and send execute_request messages containing arbitrary Python. The endpoint blocklist does not cover /api/kernels, and the websocket wrapper previously tracked idle activity without authorizing executable messages. This issue is fixed in version 3.2.6.

Affected products

mljar mercury: before 3.2.6

References

https://github.com/mljar/mercury/commit/73a40ceb0becf057f495a5738ad7f5a5222a53e1
https://github.com/mljar/mercury/releases/tag/3.2.6
https://github.com/mljar/mercury/security/advisories/GHSA-rv4m-xm3f-3ccq

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