AUGUST 24, 2026
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Case File

CVE-2026-6657

HIGH · CVSS 8.8 EPSS 0.20% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2026-06-03 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 8.8. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
arbitrary code execution code execution

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-6657
Severity
HIGH
CVSS
8.8
EPSS
0.20%

Original NVD Description

A vulnerability in jupyter-server versions 1.12.0 through 2.17.0 allows an attacker to bypass CORS origin validation when the `allow_origin_pat` configuration is used. The issue arises from the use of `re.match()` for validating the `Origin` header, which only anchors at the start of the string. This allows attacker-controlled domains such as `trusted.example.com.evil.com` to pass validation against patterns intended to match `trusted.example.com`. The vulnerability affects multiple locations in the codebase, including CORS headers, WebSocket connections, referer validation, and login redirects, potentially enabling phishing attacks, arbitrary code execution, and unauthorized access to sensitive API responses.

Related CVEs

Other vulnerabilities affecting the same vendor(s)