CVE-2026-66370

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

Score 6.1 from GitHub Security Advisory 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: 0.4%CVSS: 6.1Exploit: None knownExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.

No script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id.

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
6.1MEDIUMmedium confidence
EG Risk
28
EG Risk 28/100CISA SSVC

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%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines until it ships, then apply the release.
EPSS PROB
0.4%
EPSS %ILE
32nd
KEV
Not listed

CISA SSVCTrack at every mission impact level.

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines until it ships, then apply the release.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 6, 2026

Last Modified

August 19, 2026

Advisory Details (3)

Auto-updated Aug 6, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-66370
github_commit

commit a1e804ed997e (rrrene/html_sanitize_ex)

Fix landed in rrrene/html_sanitize_ex commit a1e804ed997e — awaiting tagged release

https://github.com/rrrene/html_sanitize_ex/commit/a1e804ed997e780ea71d14393cf2f701330553a6

Vendor Advisories for CVE-2026-66370(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 rangeFix by version rangeDependents
html_sanitize_ex0.3.1 ... 1.5.2 (21 versions)
  • 0.3.1 up to 1.4.5: fixed in 1.4.5
  • 1.5.0-rc.0 up to 1.5.3: fixed in 1.5.3
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 63× 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 144 total refreshes for this CVE.

  1. 2026-10-05 08:26 UTCEG score recompute
  2. 2026-10-05 08:26 UTCGHSA enrichment
  3. 2026-10-04 23:22 UTCEPSS rescore
  4. 2026-10-04 05:50 UTCEG score recompute
  5. 2026-10-04 05:50 UTCGHSA enrichment
  6. 2026-10-03 14:26 UTCEPSS rescore
  7. 2026-10-02 17:56 UTCEPSS rescore
  8. 2026-10-02 09:41 UTCEG score recompute
  9. 2026-10-02 09:41 UTCGHSA enrichment
  10. 2026-10-01 19:50 UTCEPSS rescore
  11. 2026-10-01 01:45 UTCEG score recompute
  12. 2026-10-01 01:45 UTCGHSA enrichment
  13. 2026-09-30 15:03 UTCEPSS rescore
  14. 2026-09-29 05:55 UTCEG score recompute
  15. 2026-09-29 05:55 UTCGHSA enrichment
  16. 2026-09-28 13:51 UTCEPSS rescore
  17. 2026-09-27 17:31 UTCEG score recompute
  18. 2026-09-27 17:31 UTCGHSA enrichment
  19. 2026-09-26 15:59 UTCEPSS rescore
  20. 2026-09-25 04:23 UTCEG score recompute
  21. 2026-09-25 04:23 UTCGHSA enrichment
  22. 2026-09-23 17:54 UTCEPSS rescore
  23. 2026-09-23 14:42 UTCEG score recompute
  24. 2026-09-23 14:42 UTCGHSA enrichment
  25. 2026-09-22 13:43 UTCEG score recompute
Show 75 more
  1. 2026-09-22 13:43 UTCGHSA enrichment
  2. 2026-09-21 12:50 UTCEG score recompute
  3. 2026-09-21 12:50 UTCGHSA enrichment
  4. 2026-09-20 20:16 UTCEPSS rescore
  5. 2026-09-20 04:05 UTCEG score recompute
  6. 2026-09-20 04:05 UTCGHSA enrichment
  7. 2026-09-19 03:13 UTCEG score recompute
  8. 2026-09-19 03:13 UTCGHSA enrichment
  9. 2026-09-18 19:28 UTCEPSS rescore
  10. 2026-09-18 01:52 UTCEG score recompute
  11. 2026-09-18 01:52 UTCGHSA enrichment
  12. 2026-09-17 00:59 UTCEG score recompute
  13. 2026-09-17 00:59 UTCGHSA enrichment
  14. 2026-09-16 14:08 UTCEPSS rescore
  15. 2026-09-16 05:15 UTCEPSS rescore
  16. 2026-09-15 14:28 UTCEG score recompute
  17. 2026-09-15 14:28 UTCGHSA enrichment
  18. 2026-09-14 10:37 UTCEG score recompute
  19. 2026-09-14 10:37 UTCGHSA enrichment
  20. 2026-09-13 09:41 UTCEG score recompute
  21. 2026-09-13 09:41 UTCGHSA enrichment
  22. 2026-09-12 08:49 UTCEG score recompute
  23. 2026-09-12 08:49 UTCGHSA enrichment
  24. 2026-09-11 14:53 UTCEPSS rescore
  25. 2026-09-11 09:37 UTCEPSS rescore
  26. 2026-09-11 07:56 UTCEG score recompute
  27. 2026-09-11 07:56 UTCGHSA enrichment
  28. 2026-09-10 07:02 UTCGHSA enrichment
  29. 2026-09-09 06:09 UTCEG score recompute
  30. 2026-09-09 06:09 UTCGHSA enrichment
  31. 2026-09-08 22:01 UTCEPSS rescore
  32. 2026-09-07 17:58 UTCEG score recompute
  33. 2026-09-07 17:58 UTCGHSA enrichment
  34. 2026-09-07 16:01 UTCEPSS rescore
  35. 2026-09-06 13:47 UTCEPSS rescore
  36. 2026-09-06 11:06 UTCEG score recompute
  37. 2026-09-06 11:06 UTCGHSA enrichment
  38. 2026-09-05 15:31 UTCEPSS rescore
  39. 2026-09-05 10:11 UTCEG score recompute
  40. 2026-09-05 10:11 UTCGHSA enrichment
  41. 2026-09-04 09:12 UTCEG score recompute
  42. 2026-09-04 09:12 UTCGHSA enrichment
  43. 2026-09-04 05:07 UTCEPSS rescore
  44. 2026-09-03 06:15 UTCEG score recompute
  45. 2026-09-03 06:15 UTCGHSA enrichment
  46. 2026-09-02 14:12 UTCEPSS rescore
  47. 2026-09-01 23:36 UTCEG score recompute
  48. 2026-09-01 23:35 UTCGHSA enrichment
  49. 2026-09-01 13:54 UTCEPSS rescore
  50. 2026-09-01 04:40 UTCEPSS rescore
  51. 2026-08-31 22:36 UTCEG score recompute
  52. 2026-08-31 22:36 UTCGHSA enrichment
  53. 2026-08-30 19:17 UTCEPSS rescore
  54. 2026-08-30 11:40 UTCEG score recompute
  55. 2026-08-30 11:40 UTCGHSA enrichment
  56. 2026-08-30 01:22 UTCEPSS rescore
  57. 2026-08-29 10:41 UTCEG score recompute
  58. 2026-08-29 10:41 UTCGHSA enrichment
  59. 2026-08-28 21:42 UTCEPSS rescore
  60. 2026-08-27 20:42 UTCEG score recompute
  61. 2026-08-27 20:42 UTCGHSA enrichment
  62. 2026-08-26 19:39 UTCEG score recompute
  63. 2026-08-26 19:39 UTCGHSA enrichment
  64. 2026-08-26 14:47 UTCEPSS rescore
  65. 2026-08-25 18:45 UTCEG score recompute
  66. 2026-08-25 18:45 UTCGHSA enrichment
  67. 2026-08-25 13:49 UTCEPSS rescore
  68. 2026-08-24 17:52 UTCEG score recompute
  69. 2026-08-24 17:52 UTCGHSA enrichment
  70. 2026-08-23 17:00 UTCEG score recompute
  71. 2026-08-23 17:00 UTCGHSA enrichment
  72. 2026-08-23 00:19 UTCEPSS rescore
  73. 2026-08-22 16:08 UTCEG score recompute
  74. 2026-08-22 16:08 UTCGHSA enrichment
  75. 2026-08-21 23:49 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-66370?
CVE-2026-66370 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 an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction…
When was CVE-2026-66370 disclosed?
CVE-2026-66370 was first published 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-2026-66370 actively exploited?
CVE-2026-66370 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (32nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66370?
CVE-2026-66370 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-66370?
An upstream fix for CVE-2026-66370 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-66370 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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