CVE-2026-40110: Jupyter Server is the backend for Jupyter web applications

Q: How do I fix CVE-2026-40110?

jupyter server: upgrade to 2.18.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-40110 being exploited?

CVE-2026-40110 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-40110 affect?

CVE-2026-40110 affects jupyter server. Severity is high (CVSS 7.3). 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()

Routine

HIGH 7.3UPGRADE

CVE-2026-40110 is a high-severity flaw (CVSS 7.3) affecting jupyter server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-777, CWE-625
Published	2026-05-05
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: jupyter

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-05 22:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

jupyter jupyter server UPGRADE

Affected: < 2.18.0

Fixed in: 2.18.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy jupyter-server || rpm -q jupyter-server || jupyter-server --version

2. UPGRADE to 2.18.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade jupyter-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade jupyter-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40110?

jupyter server: upgrade to 2.18.0. Exact commands for each OS are on this page.

Is CVE-2026-40110 being exploited?

CVE-2026-40110 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40110 affect?

CVE-2026-40110 affects jupyter server. Severity is high (CVSS 7.3). 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()

How urgent is CVE-2026-40110?

Priority 32/100. High severity

Software pages

Python vulnerabilities · Jupyter vulnerabilities

Related CVEs

CVE-2026-44727 MEDIUM 5.4 UPGRADE Jupyter Server is the backend for Jupyter web applications
CVE-2025-61669 MEDIUM 6.1 UPGRADE Jupyter Server is the backend for Jupyter web applications
CVE-2026-35397 HIGH 8.8 UPGRADE Jupyter Server is the backend for Jupyter web applications
CVE-2026-40934 MEDIUM 6.8 UPGRADE Jupyter Server is the backend for Jupyter web applications
CVE-2026-5422 HIGH 8.1 DOWNGRADE A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boun

References

← Back to latest CVEs