CVE-2026-66829

MEDIUMNVD 6.16.1—
EchelonGraph scoreHIGH confidence

Score 6.1 from GitHub Security Advisory (severity: LOW) published 2026-08-06. NVD baseline CVSS 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.1Exploit: None knownExposed: 0

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

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker's choosing via a element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy.

This is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.

This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

CVSS v3
6.1
EG Score
6.1(high)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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
Severity61% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
41%
KEV
Not listed

Published

August 6, 2026

Last Modified

August 19, 2026

Advisory Details (3)

Auto-updated Aug 11, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-66829
github_commit

commit 9f7e38be51ed (rrrene/html_sanitize_ex)

Fix landed in rrrene/html_sanitize_ex commit 9f7e38be51ed — awaiting tagged release

https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f
generic

CVE-2026-66829

https://cna.erlef.org/cves/CVE-2026-66829.html

Vendor Advisories for CVE-2026-66829(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)
Hex(1)
PackageVulnerable rangeFixed inDependents
html_sanitize_ex0.3.1 ... 1.5.2 (21 versions)1.5.3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 39× 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. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-20 14:19 UTCEG score recompute
  3. 2026-08-20 14:19 UTCGHSA enrichment
  4. 2026-08-19 17:04 UTCEPSS rescore
  5. 2026-08-19 12:25 UTCGHSA enrichment
  6. 2026-08-19 12:00 UTCEG score recompute
  7. 2026-08-19 12:00 UTCGHSA enrichment
  8. 2026-08-18 20:20 UTCEG score recompute
  9. 2026-08-18 20:20 UTCGHSA enrichment
  10. 2026-08-18 13:48 UTCEPSS rescore
  11. 2026-08-17 19:25 UTCEG score recompute
  12. 2026-08-17 19:25 UTCGHSA enrichment
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-16 18:24 UTCEG score recompute
  15. 2026-08-16 18:24 UTCGHSA enrichment
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-15 17:30 UTCEG score recompute
  18. 2026-08-15 17:30 UTCGHSA enrichment
  19. 2026-08-15 01:30 UTCEPSS rescore
  20. 2026-08-14 16:35 UTCEG score recompute
  21. 2026-08-14 16:35 UTCGHSA enrichment
  22. 2026-08-13 22:00 UTCEPSS rescore
  23. 2026-08-13 15:41 UTCGHSA enrichment
  24. 2026-08-12 14:47 UTCEG score recompute
  25. 2026-08-12 14:47 UTCGHSA enrichment
Show 14 more
  1. 2026-08-12 13:51 UTCEPSS rescore
  2. 2026-08-11 13:53 UTCEG score recompute▲ 3.80
  3. 2026-08-11 13:53 UTCGHSA enrichment
  4. 2026-08-11 13:52 UTCNVD updateCVSS v3 → 6.1 · severity → MEDIUM
  5. 2026-08-11 00:00 UTCEPSS rescore
  6. 2026-08-10 20:19 UTCEG score recompute
  7. 2026-08-10 20:19 UTCGHSA enrichment
  8. 2026-08-09 13:47 UTCEPSS rescore
  9. 2026-08-08 16:37 UTCEPSS rescore
  10. 2026-08-07 13:51 UTCGHSA enrichment
  11. 2026-08-06 22:38 UTCGHSA enrichment
  12. 2026-08-06 16:32 UTCEG score recompute
  13. 2026-08-06 15:31 UTCEG score recompute
  14. 2026-08-06 15:31 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-66829?
CVE-2026-66829 is a medium vulnerability published on August 6, 2026. URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene htmlsanitizeex allows a remote attacker to force visitors of a page to navigate to a site of the attacker's choosing via a <meta http-equiv="refresh"> element in sanitized HTML. HtmlSanitizeEx.html5/1…
When was CVE-2026-66829 disclosed?
CVE-2026-66829 was first published in the National Vulnerability Database on August 6, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66829 actively exploited?
CVE-2026-66829 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 59.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66829?
CVE-2026-66829 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-66829?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66829, 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

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