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Fencer Vulns
medium 6.1

CVE-2020-11888 json

XSS in python-markdown2

published 2020-04-20 6 y ago modified 2026-06-17 4 mo ago also GHSA-fv3h-8x5j-pvgq , PYSEC-2020-65 , EUVD-2020-0105

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.9%
EPSS 1.9% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

python-markdown2 through 2.3.8 allows XSS because element names are mishandled unless a \w+ match succeeds. For example, an attack might use elementname@ or elementname- with an onclick attribute.

Patch / fix

  • pypi markdown2 2.3.9
  • python-markdown2 Debian 14, Debian 13, Debian 12 2.3.9-1

debian advisories DEBIAN-CVE-2020-11888

  • python-markdown2 Package Hub 15 SP1 2.3.7-bp151.2.3.1
  • python-markdown2 openSUSE Leap 15.1 2.3.7-lp151.2.3.1

opensuse advisories openSUSE-SU-2020:0656-1openSUSE-SU-2020:0651-1

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-2020-11888 updated cvss 8.0

python-markdown2: Unsanitized input allows for cross-site scripting (XSS)

  • 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

1.93% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/trentm/python-markdown2/issues/348 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi markdown2
<2.3.9
2.3.9

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.