jupyter jupyter-server up to up to 2.17.0 re.match origin validation

Summaryinfo

A vulnerability was found in jupyter jupyter-server up to up to 2.17.0. It has been rated as critical. This vulnerability affects the function re.match. Performing a manipulation results in origin validation. This vulnerability is identified as CVE-2026-6657. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in jupyter jupyter-server up to up to 2.17.0. It has been classified as critical. This affects the function re.match. The manipulation with an unknown input leads to a origin validation vulnerability. CWE is classifying the issue as CWE-346. The product does not properly verify that the source of data or communication is valid. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at huntr.com. This vulnerability is uniquely identified as CVE-2026-6657 since 04/20/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/03/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• jupyter

Name

• jupyter-server

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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Exploitinginfo

Threat Intelligenceinfo

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Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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