CVE-2021-23165

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-03-17. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in htmldoc before v1.9.12. Heap buffer overflow in pspdf_prepare_outpages(), in ps-pdf.cxx may lead to execute arbitrary code and denial of service.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
87.2%
KEV
Not listed

Published

March 16, 2022

Last Modified

February 5, 2025

Advisory Details (4)

Auto-updated Jun 29, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, redhat.
generic

Issue · GitHub

https://github.com/michaelrsweet/htmldoc/issues/413
generic
https://github.com/michaelrsweet/htmldoc/commit/6e8a95561988500b5b5ae4861b3b0cbf4fba517f.patch
github_commit

commit 6e8a95561988 (michaelrsweet/htmldoc)

Fix landed in michaelrsweet/htmldoc commit 6e8a95561988 — awaiting tagged release

https://github.com/michaelrsweet/htmldoc/commit/6e8a95561988500b5b5ae4861b3b0cbf4fba517f
redhat

1967014 – (CVE-2021-23165) CVE-2021-23165 htmldoc: heap-buffer-overflow in pspdf_prepare_outpages()

https://bugzilla.redhat.com/show_bug.cgi?id=1967014

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuhtmldoc-common (1.9.7-1ubuntu0.3) @ focal2026-05-26ubuntu
ubuntuhtmldoc-common (1.8.27-8ubuntu1.1+esm1) @ xenial2026-05-26ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-23 01:57 UTCEG score recompute
  2. 2026-07-22 22:44 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
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  9. 2026-06-29 18:23 UTCOSV refresh
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  39. 2026-06-12 07:06 UTCOSV refresh
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  73. 2026-05-26 01:33 UTCEG score recompute
  74. 2026-05-26 01:33 UTCVendor advisory
  75. 2026-05-26 01:33 UTCGHSA enrichment

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Frequently asked(5)

What is CVE-2021-23165?
CVE-2021-23165 is a critical vulnerability published on March 16, 2022. A flaw was found in htmldoc before v1.9.12. Heap buffer overflow in pspdfprepareoutpages(), in ps-pdf.cxx may lead to execute arbitrary code and denial of service.
When was CVE-2021-23165 disclosed?
CVE-2021-23165 was first published in the National Vulnerability Database on March 16, 2022, with the most recent update on February 5, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-23165 actively exploited?
CVE-2021-23165 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 87.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-23165?
CVE-2021-23165 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-23165?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-23165, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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