No exploitation reportedFix available

CVE-2018-21030

Q: Is CVE-2018-21030 actively exploited?

Active exploitation of CVE-2018-21030 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2018-21030?

CVE-2018-21030 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

No exploitation reported by the sources we read.

Published2019-10-31
Fixed in5.5.0 · 5.5.0rc1
WeaknessCWE-79 · CWE-863

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Jupyter Notebook before 5.5.0 does not use a CSP header to treat served files as belonging to a separate origin. Thus, for example, an XSS payload can be placed in an SVG document.

Timeline

dates in UTC

2019-10-3115:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2018-21030?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2018-21030?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Jupyter notebook

Branch	Affected	Fixed in	Source
5.5	< 5.5.0	5.5.0	NVD · OSV
5.5	< 5.5.0rc1	5.5.0rc1	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Jupyter notebook to 5.5.0 · 5.5.0rc1

Advisories and patches

github.comPatch
github.comRelease Notes

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.15.3read 2026-10-23
NVDCVSS 2.05read 2026-10-23
NVDweakness (CWE)CWE-79, CWE-863read 2026-10-23
FIRST EPSSEPSS score1.4 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published: 2019-10-31
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2018-21030?

Jupyter Notebook before 5.5.0 does not use a CSP header to treat served files as belonging to a separate origin. Thus, for example, an XSS payload can be placed in an SVG document.

Is CVE-2018-21030 actively exploited?

Active exploitation of CVE-2018-21030 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-21030?

CVE-2018-21030 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

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