CVE-2026-66843

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM 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: 0.5%CVSS: 6.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase "javascript:", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive.

This is not unconditional cross-site scripting. A javascript: URL does not execute through in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path.

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%
Exploitation1% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

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 11, 2026
Patch available. Sources: github_commit.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-66843
github_commit

commit bec27fec4de9 (rrrene/html_sanitize_ex)

Fix landed in rrrene/html_sanitize_ex commit bec27fec4de9 — awaiting tagged release

https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf
generic

CVE-2026-66843

https://cna.erlef.org/cves/CVE-2026-66843.html

Vendor Advisories for CVE-2026-66843(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 / 66× 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 146 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-66843?
CVE-2026-66843 is a medium vulnerability published on August 6, 2026. Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene htmlsanitizeex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing…
When was CVE-2026-66843 disclosed?
CVE-2026-66843 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-2026-66843 actively exploited?
CVE-2026-66843 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66843?
CVE-2026-66843 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-66843?
A fix for CVE-2026-66843 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66843 are linked in the Vendor Advisories panel on this page.

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