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NVD / CVE Program· CNA mitre

CVE-2021-43579: 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 docum

Noroxi assessment

Priority: Monitor (action score 33/100)

  • Public proof-of-concept code exists (Exploit-DB); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 7.3% (FIRST EPSS); higher than 94.3% of all records.
  • Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: htmldoc (Debian:12) 1.9.13-1; htmldoc (Debian:9) 1.8.27-8+deb9u2; htmldoc (openSUSE:Tumbleweed) 1.9.14-1.1.

Low priority for now. Upgrade to htmldoc (Debian:12) 1.9.13-1; htmldoc (Debian:9) 1.8.27-8+deb9u2; htmldoc (openSUSE:Tumbleweed) 1.9.14-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.8 · v3.1—Proof of concept Fix available
Published
Jan 10, 2022
Updated
Jun 17, 2026
EPSS
7.3% · 94th percentile

Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 7.3%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-43579

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
htmldoc projecthtmldoc
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux9.0
  • htmldoc project htmldocup to 1.9.13 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12htmldocbefore 1.9.13-11.9.13-1
Debian:9htmldocbefore 1.8.27-8+deb9u21.8.27-8+deb9u2
openSUSE:Tumbleweedhtmldocbefore 1.9.14-1.11.9.14-1.1
SUSE:Subscription Management Tool 11 SP3htmldocbefore 1.8.27-170.4.6.11.8.27-170.4.6.1

Same product

htmldoc project: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-23165A flaw was found in htmldoc before v1.9.12.
    40Plan
  • CVE-2021-23158A flaw was found in htmldoc in v1.9.12.
    40Plan
  • CVE-2021-20308Integer overflow in the htmldoc 1.9.11 and before may allow attackers to execute arbitrary code and cause a denial of service that is simila
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2019-19630Dec 7, 2019 · HTMLDOC 1.9.7 allows a stack-based buffer overflow in the hd_strlcpy() function in string.c (when called from render_contents in ps-pdf.cxx)
    31Monitor
  • ← EarlierCVE-2021-40985Nov 3, 2021 · A stack-based buffer under-read in htmldoc before 1.9.12, allows attackers to cause a denial of service via a crafted BMP image to image_loa
    22Monitor
  • Later →CVE-2022-0534Feb 9, 2022 · A vulnerability was found in htmldoc version 1.9.15 where the stack out-of-bounds read takes place in gif_get_code() and occurs when opening
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:htmldoc1.9.13-1 · Debian:12Package registry (OSV)
opensuse:htmldoc1.9.14-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:htmldoc1.8.27-170.4.6.1 · SUSE:Subscription Management Tool 11 SP3Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entryremote2025-09-16

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+1345 d
  3. TodayOct 29, 2026+1753 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records