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Fencer Vulns
high 7.8

CVE-2021-23180 json

A flaw was found in htmldoc in v1.9.12 and before.

published 2022-03-02 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-10290

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

A flaw was found in htmldoc in v1.9.12 and before. Null pointer dereference in file_extension(),in file.c may lead to execute arbitrary code and denial of service.

Patch / fix

  • htmldoc Debian 14, Debian 13, Debian 12 1.9.11-4

debian advisories DEBIAN-CVE-2021-23180

  • htmldoc Ubuntu 20.04 LTS 1.9.7-1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2021-23180

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • htmldoc Arch Linux 1.9.12-1

arch linux advisories AVG-1773

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-2021-23180 updated cvss 8.6

htmldoc: null pointer dereference in function in file_extension()

  • 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

1.35% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/michaelrsweet/htmldoc/issues/418 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • n/a htmldoc

Classification

Weakness

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.