How severe is CVE-2021-34121?

CVE-2021-34121 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-34121 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34121?

CVE-2021-34121 affects Htmldoc Project Htmldoc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-34121?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-34121 published?

CVE-2021-34121 was published on 2023-07-18 and last updated on 2026-06-17.

CVE-2021-34121

CVE-2021-34121 is a high-severity vulnerability in Htmldoc Project Htmldoc with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Htmldoc Project Htmldoc
Published: 2023-07-18
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-34121?: 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.
How severe is CVE-2021-34121?: CVE-2021-34121 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-34121 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34121?: CVE-2021-34121 affects Htmldoc Project Htmldoc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-34121?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-34121 published?: CVE-2021-34121 was published on 2023-07-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:htmldoc_project:htmldoc:1.9.12:*:*:*:*:*:*:*

More vulnerabilities in Htmldoc Project Htmldoc

CVE-2024-46478 — Critical (CVSS 9.8): HTMLDOC v1.9.18 contains a buffer overflow in parse_pre function,ps-pdf.cxx:5681.
CVE-2024-45508 — Critical (CVSS 9.8): HTMLDOC before 1.9.19 has an out-of-bounds write in parse_paragraph in ps-pdf.cxx because of an attempt to strip…
CVE-2021-23165 — Critical (CVSS 9.8): A flaw was found in htmldoc before v1.9.12. Heap buffer overflow in pspdf_prepare_outpages(), in ps-pdf.cxx may lead to…
CVE-2021-23158 — Critical (CVSS 9.8): A flaw was found in htmldoc in v1.9.12. Double-free in function pspdf_export(),in ps-pdf.cxx may result in a…
CVE-2021-20308 — Critical (CVSS 9.8): Integer overflow in the htmldoc 1.9.11 and before may allow attackers to execute arbitrary code and cause a denial of…
CVE-2021-34119 — High (CVSS 7.8): A flaw was discovered in htmodoc 1.9.12 in function parse_paragraph in ps-pdf.cxx ,this flaw possibly allows possible…

All CVEs affecting Htmldoc Project Htmldoc →

Other CWE-125 (Out-of-bounds Read) vulnerabilities

CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →