CVE-2026-8445

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-23. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via to_markdown(). While a small set of Markdown metacharacters are escaped, characters such as < and > are preserved, so untrusted input that is safe in to_html() — including entity-decoded text (e.g. <script>) or text from RCDATA/RAWTEXT-parsed elements like , , , and — can be emitted as raw HTML in the Markdown output, enabling a sanitizer bypass and potential cross-site scripting when that output is rendered.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
75(Attend)
EG Risk 75/100SSVC: Attend

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%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

August 23, 2026

Last Modified

August 26, 2026

Advisory Details (2)

Auto-updated Aug 26, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Sanitizer Bypass (in Markdown) · Advisory · EmilStenstrom/justhtml · GitHub

https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-3rcm-vjrc-p45j
generic

justhtml before 1.12.0 Sanitizer Bypass via Markdown | Advisories | VulnCheck

https://www.vulncheck.com/advisories/justhtml-before-sanitizer-bypass-via-markdown

Vendor Advisories for CVE-2026-8445(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
justhtml0.1.0 ... 1.9.1 (56 versions)1.12.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 34× in last 7d / 34× 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.

  1. 2026-08-26 21:10 UTCGHSA enrichment
  2. 2026-08-26 17:24 UTCEG score recompute
  3. 2026-08-26 17:24 UTCGHSA enrichment
  4. 2026-08-26 14:47 UTCEPSS rescore
  5. 2026-08-26 13:41 UTCGHSA enrichment
  6. 2026-08-26 09:56 UTCGHSA enrichment
  7. 2026-08-26 06:11 UTCGHSA enrichment
  8. 2026-08-26 02:26 UTCGHSA enrichment
  9. 2026-08-25 22:41 UTCGHSA enrichment
  10. 2026-08-25 18:56 UTCGHSA enrichment
  11. 2026-08-25 15:12 UTCEG score recompute
  12. 2026-08-25 15:12 UTCGHSA enrichment
  13. 2026-08-25 13:49 UTCEPSS rescore
  14. 2026-08-25 11:26 UTCGHSA enrichment
  15. 2026-08-25 07:41 UTCGHSA enrichment
  16. 2026-08-25 03:57 UTCGHSA enrichment
  17. 2026-08-25 00:12 UTCGHSA enrichment
  18. 2026-08-24 20:26 UTCEG score recompute
  19. 2026-08-24 20:26 UTCGHSA enrichment
  20. 2026-08-24 19:22 UTCEG score recompute
  21. 2026-08-24 19:22 UTCGHSA enrichment
  22. 2026-08-24 16:55 UTCEG score recompute
  23. 2026-08-24 16:55 UTCGHSA enrichment
  24. 2026-08-24 14:18 UTCEPSS rescore
  25. 2026-08-24 12:50 UTCGHSA enrichment
Show 9 more
  1. 2026-08-24 09:05 UTCGHSA enrichment
  2. 2026-08-24 05:20 UTCGHSA enrichment
  3. 2026-08-24 01:35 UTCGHSA enrichment
  4. 2026-08-23 21:50 UTCGHSA enrichment
  5. 2026-08-23 18:05 UTCEG score recompute
  6. 2026-08-23 18:05 UTCGHSA enrichment
  7. 2026-08-23 14:20 UTCEG score recompute
  8. 2026-08-23 13:51 UTCEG score recompute
  9. 2026-08-23 13:50 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-8445?
CVE-2026-8445 is a critical vulnerability published on August 23, 2026. justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via tomarkdown(). While a small set of Markdown metacharacters are escaped, characters such as < and > are preserved, so…
When was CVE-2026-8445 disclosed?
CVE-2026-8445 was first published in the National Vulnerability Database on August 23, 2026, with the most recent update on August 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8445 actively exploited?
CVE-2026-8445 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 69.1% of all scored CVEs.
What is the CVSS score of CVE-2026-8445?
CVE-2026-8445 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-8445?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8445, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-8445

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