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CVE-2021-40985· NVD / CVE Program· CNA mitre

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

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_load_bmp.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Nov 3, 2021
Updated
Jun 17, 2026
EPSS
0.9% · 59th percentile
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Report tools

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Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

Affected systems

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 htmldocbefore 1.9.12

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 1.9.12-2.11.9.12-2.1
SUSE:Subscription Management Tool 11 SP3htmldocbefore 1.8.27-170.4.3.11.8.27-170.4.3.1

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
  • CVE-2024-46478HTMLDOC v1.9.18 contains a buffer overflow in parse_pre function,ps-pdf.cxx:5681.
    39Monitor
  • CVE-2024-45508HTMLDOC before 1.9.19 has an out-of-bounds write in parse_paragraph in ps-pdf.cxx because of an attempt to strip leading whitespace from a w
    39Monitor
  • CVE-2021-43579A 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
    33Monitor

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:htmldoc1.9.12-2.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:htmldoc1.8.27-170.4.3.1 · SUSE:Subscription Management Tool 11 SP3Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

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.

No dated events beyond publication.

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

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

ATT&CK techniques

—

Noroxi analysis

No Noroxi analysis for this record yet

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We use this product, ask for help

Change log

  1. Fix✗ → ✓

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

References

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

All records