Review reviewHigh

CVE-2026-40110

jupyter-server jupyter_server, Red Hat Migration Toolkit for Applications 8.2, Red Hat OpenShift AI (RHOAI)

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.match() to check incoming origins against the allow_origin_pat configuration value. Because re.match() only anchors at the start of the string and does not require a full match, a pattern intended to match only a trusted domain (e.g., trusted.example.com) will also match any origin that begins with that domain followed by additional characters (e.g., trusted.example.com.evil.com). An attacker who controls such a domain can bypass the CORS origin restricti...

CVSS: 7.6
EPSS: 0.34%
CISA KEV: Not listed
Published: 2026.05.06

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.34%

Technical severityCVSS 7.6

Vulnerability overview

Affected product and versions

Product: jupyter-server jupyter_server, Red Hat Migration Toolkit for Applications 8.2, Red Hat OpenShift AI (RHOAI)
Affected versions: >= <= 2.17.0, < 2.18.0
Fixed versions: 2.18.0

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that jupyter-server jupyter_server, Red Hat Migration Toolkit for Applications 8.2, Red Hat OpenShift AI (RHOAI) and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE: CWE-625, CWE-777