CVE-2020-26215 in Notebook
Summary
by MITRE • 11/19/2020
Jupyter Notebook before version 6.1.5 has an Open redirect vulnerability. A maliciously crafted link to a notebook server could redirect the browser to a different website. All notebook servers are technically affected, however, these maliciously crafted links can only be reasonably made for known notebook server hosts. A link to your notebook server may appear safe, but ultimately redirect to a spoofed server on the public internet. The issue is patched in version 6.1.5.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/08/2020
The vulnerability identified as CVE-2020-26215 represents a critical open redirect flaw within Jupyter Notebook versions prior to 6.1.5, exposing users to potential phishing and social engineering attacks. This security weakness allows attackers to craft malicious links that can redirect users from a legitimate notebook server to a fraudulent website, even when the original link appears trustworthy to the user. The vulnerability specifically affects the notebook server's handling of redirect parameters, creating an attack vector where users might unknowingly navigate to malicious sites while believing they are accessing their legitimate Jupyter environment. The flaw is particularly concerning because it operates at the application layer, leveraging the legitimate redirect functionality that Jupyter Notebook uses for various navigation purposes.
Technical exploitation of this vulnerability occurs when an attacker crafts a URL containing a malicious redirect parameter that points to an external domain while maintaining the appearance of a legitimate notebook server address. The vulnerability stems from insufficient validation of redirect targets within the notebook server's URL handling mechanism, allowing arbitrary redirection without proper domain verification or security checks. This issue is categorized under CWE-601 Open Redirect vulnerability, which is classified as a security weakness that enables attackers to redirect users to malicious websites by manipulating URL parameters. The flaw is particularly dangerous because it can be executed against any notebook server that has not been updated to version 6.1.5, making it a widespread concern across various organizations and research environments.
The operational impact of this vulnerability extends beyond simple phishing attempts, as it can enable more sophisticated attacks including credential harvesting, malware distribution, and data exfiltration. When users are redirected to a spoofed server, they may unknowingly enter credentials or sensitive information into what they believe is their legitimate notebook environment. This vulnerability particularly affects research institutions, data science teams, and organizations that rely heavily on Jupyter Notebook for collaborative work, as the attack surface is broad and the redirection can occur through various communication channels including email, shared documents, or internal messaging systems. The attack vector aligns with ATT&CK technique T1566.001 Phishing, where the malicious redirect serves as a delivery mechanism for more comprehensive attacks.
Organizations should prioritize immediate patching of all Jupyter Notebook installations to version 6.1.5 or later to remediate this vulnerability. Additionally, network administrators should implement URL filtering and monitoring solutions to detect suspicious redirect patterns, while security teams should educate users about verifying URL authenticity before clicking on links. The mitigation strategy should include implementing proper input validation for redirect parameters, establishing domain whitelisting for legitimate redirect destinations, and monitoring for unusual redirect activities within notebook server logs. Regular security assessments should verify that the patched version is properly deployed across all environments, including cloud deployments and containerized instances. Organizations should also consider implementing additional security controls such as content security policies and web application firewalls to provide defense-in-depth against similar vulnerabilities.