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Fencer Vulns
high 7.8

CVE-2021-43579 json

A stack-based buffer overflow in image_load_bmp() in HTMLDOC <= 1.9.13 results in remote code execution if the victim converts an HTML docu…

published 2021-11-12 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30494

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.3%
EPSS 7.3% chance of exploitation in 30 days, percentile 94%
public exploits
1
Exploit-DB

Summary

A stack-based buffer overflow in image_load_bmp() in HTMLDOC <= 1.9.13 results in remote code execution if the victim converts an HTML document linking to a crafted BMP file.

Patch / fix

  • htmldoc Debian 14, Debian 13, Debian 12 1.9.13-1

debian advisories DEBIAN-CVE-2021-43579

  • htmldoc Ubuntu Pro 14.04 LTS 1.8.27-8ubuntu1+esm3
  • htmldoc Ubuntu Pro 16.04 LTS 1.8.27-8ubuntu1.1+esm2
  • htmldoc Ubuntu Pro 18.04 LTS 1.9.2-1ubuntu0.2+esm1
  • htmldoc Ubuntu Pro 20.04 LTS 1.9.7-1ubuntu0.3+esm1

ubuntu advisories UBUNTU-CVE-2021-43579

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 Subscription Management Tool 11 SP3 1.8.27-170.4.6.1

suse advisories SUSE-SU-2022:14877-1

  • htmldoc openSUSE Tumbleweed 1.9.14-1.1

opensuse advisories openSUSE-SU-2024:11741-1

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-2021-43579 updated cvss 8.8

htmldoc: stack-based buffer overflow in image_load_bmp() in htmldoc/image.cxx

  • 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

Timeline

  1. Published
  2. First public exploit (EDB-52425)

Exploit prediction

7.35% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-52425 HTMLDOC 1.9.13 - Stack Buffer Overflow remote, 2025-09-16
  • github.com https://github.com/michaelrsweet/htmldoc/issues/453 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/michaelrsweet/htmldoc/issues/456 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

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.