CVE catalog
CVE-2026-6657
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
- Severity
- High · CVSS 8.8
- Published
- Source
- [NVD] · [CVE record]
- EPSS
- 6.18% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | jupyter-server | sid | 2.20.0-3 | vulnerable |
| Debian | jupyter-server | forky | 2.20.0-3 | vulnerable |
| Debian | jupyter-server | trixie | 2.15.0-1 | vulnerable |
| Debian | jupyter-server | bookworm | 1.23.3-1 | vulnerable |
| Cpe | jupyter-server | Not reported | Not reported | vulnerable |
| Cpe | jupyter_server | Not reported | Not reported | unknown |
| PyPI | jupyter-server | Not reported | Not reported | unknown |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | jupyter-server | source | sid | (unfixed) | not yet assigned | Not reported | Not reported |
| Debian | jupyter-server | source | forky | (unfixed) | not yet assigned | Not reported | Not reported |
| Debian | jupyter-server | source | trixie | (unfixed) | not yet assigned | Not reported | Not reported |
| Debian | jupyter-server | source | bookworm | (unfixed) | not yet assigned | Not reported | Not reported |
Notes
[trixie] jupyter-server: Minor issue [bookworm] jupyter-server: Minor issue; unanchored allow_origin_pat re.match present, revisit with next update
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [jupyter-server]Affected
Details (2)
1.23.3-1· all · bookwormAffected
nvd · jupyter-server · debian · bookworm; nvd · jupyter-server · debian · 12
1.23.3-1· all · bookwormAffected
nvd · jupyter-server · debian · bookworm; nvd · jupyter-server · debian · 12
- [python3-jupyter-server]Affected
Source package: [jupyter-server]
Details (2)
1.23.3-1· all · bookwormAffected
nvd · jupyter-server · debian · bookworm; nvd · jupyter-server · debian · 12
1.23.3-1· all · bookwormAffected
nvd · jupyter-server · debian · bookworm; nvd · jupyter-server · debian · 12
[Debian 13 (Trixie)]
- [jupyter-server]Affected
Details (2)
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
- [python3-jupyter-server]Affected
Source package: [jupyter-server]
Details (2)
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
- [python-jupyter-server-doc]Affected
Source package: [jupyter-server]
Details (2)
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
2.15.0-1· all · trixieAffected
nvd · jupyter-server · debian · 13
Observed:
References
- [https://nvd.nist.gov/vuln/detail/CVE-2026-6657]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-6657]
- [https://osv.dev/vulnerability/PYSEC-2026-3472]
- [https://security-tracker.debian.org/tracker/CVE-2026-6657]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6657.json]
[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]