HOMEVULNERABILITIESCVE-2021-34121
HIGH

CVE-2021-34121

CWE-125Published: July 18, 2023· Updated: Jun 17, 2026

7.8
CVSS v3.1

Official Description

An Out of Bounds flaw was discovered in htmodoc 1.9.12 in function parse_tree() in toc.cxx, this possibly leads to memory layout information leaking in the data. This might be used in a chain of vulnerability in order to reach code execution.

NVD Source

Technical Analysis

CVE-2021-34121 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors & Products

htmldoc_project1 product(s)
htmldoc
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/michaelrsweet/htmldoc/commit/c67bbd8756f015e33e4ba639a40c7f9d8bd9e8ab
PATCHhttps://github.com/michaelrsweet/htmldoc/commit/c67bbd8756f015e33e4ba639a40c7f9d8bd9e8ab

All References (4)

→
https://github.com/michaelrsweet/htmldoc/commit/c67bbd8756f015e33e4ba639a40c7f9d8bd9e8abPatch
→
https://github.com/michaelrsweet/htmldoc/issues/433Exploit · Issue Tracking
→
https://github.com/michaelrsweet/htmldoc/commit/c67bbd8756f015e33e4ba639a40c7f9d8bd9e8abPatch
→
https://github.com/michaelrsweet/htmldoc/issues/433Exploit · Issue Tracking

Quick Facts

CVE IDCVE-2021-34121
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-125
CISA KEVNo
Affected1 vendor(s)
PublishedJul 18, 2023

Related CVEs (CWE-125)

CVE-2021-41556
10.0
CVE-2021-21777
10.0
CVE-2013-0767
10.0
CVE-2017-14451
10.0
CVE-2009-2523
10.0
CVE-2023-26489
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-34121 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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