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CVE-2021-23180

26
FAUCET Score

CVE-2021-23180 describes a null pointer dereference vulnerability in htmldoc versions 1.9.12 and earlier, specifically within the file_extension() function in file.c. This flaw carries a high CVSS score of 7.8, indicating that an attacker could achieve arbitrary code execution or denial of service through a low-complexity attack requiring user interaction. While the potential impact is significant, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or notable community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.9.12CPE matchmatch criteria
cpe:2.3:a:htmldoc_project:htmldoc:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.35%
Probability of exploitation in next 30 days
EPSS Percentile
68.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0135 is in the 67th percentile among its peer group of 11,621 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia nvd_reference
View patch

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
github.com / michaelrsweet/htmldoc/commit/19c582fb32eac74b57e155cffbb529377a9e751a
PatchThird Party Advisory
github.com / michaelrsweet/htmldoc/issues/418
ExploitIssue TrackingThird Party Advisory
ubuntu.com / security/CVE-2021-23180
Third Party Advisory