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Fencer Vulns
high 7.5

CVE-2021-32862 json

nbconvert vulnerable to cross-site scripting (XSS) via multiple exploit paths

published 2022-08-10 4 y ago modified 2026-09-10 1 mo ago also GHSA-9jmq-rx5f-8jwq , GHSA-h274-fcvj-h2wm , PYSEC-2022-249 , EUVD-2022-0161

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

The GitHub Security Lab discovered sixteen ways to exploit a cross-site scripting vulnerability in nbconvert. When using nbconvert to generate an HTML version of a user-controllable notebook, it is possible to inject arbitrary HTML which may lead to cross-site scripting (XSS) vulnerabilities if these HTML notebooks are served by a web server (eg: nbviewer).

Patch / fix

  • pypi nbconvert 6.3.0a0, 6.5.1
  • nbconvert Debian 14, Debian 13, Debian 12 6.5.1-1

debian advisories DEBIAN-CVE-2021-32862

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-32862 updated cvss 7.5

nbconvert: arbitrary html injection

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.52% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jupyter/nbconvert/security/advisories/GHSA-9jmq-rx5f-8jwq referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi nbconvert
<6.5.1
<6.3.0a0
6.5.1
6.3.0a0

Affected products

  • jupyter nbconvert

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.