CVE-2026-66296

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

Score 6.1 from GitHub Security Advisory published 2026-08-03. 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 weekElevated
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: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler.

Oaskit.ErrorHandler.Default.format_reason/4 and Oaskit.ErrorHandler.Default.reason_to_html/1 in lib/oaskit/error_handler/default.ex render request-validation failures as an HTML page whenever the request's Accept header contains html, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or deepObject query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under additionalProperties: false), and the raw Content-Type header, reflected in unsupported-media-type errors when it fails to parse.

Because browsers send Accept: text/html on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom Content-Type, or attacker-controlled script on the victim's side is required. A payload such as filter[alert(document.domain)]=x terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses.

Both HTML error rendering and the vulnerable handler are enabled by default: Oaskit.Plugs.ValidateRequest defaults :html_errors to true and :error_handler to Oaskit.ErrorHandler.Default, so applications following the documented usage are affected without any opt-in.

This issue affects oaskit: from 0.1.0 before 0.14.1.

CVSS v3
6.1
EG Score
6.1MEDIUMmedium confidence
EG Risk
43
EG Risk 43/100CISA 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%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
28th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation public PoC (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 3, 2026

Last Modified

August 17, 2026

Advisory Details (4)

Auto-updated Aug 3, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit

commit b70c6b2eaf0b (lud/oaskit)

Fix landed in lud/oaskit commit b70c6b2eaf0b — awaiting tagged release

https://github.com/lud/oaskit/commit/b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-66296
generic

CVE-2026-66296

https://cna.erlef.org/cves/CVE-2026-66296.html
githubMentions a patch (unverified)🟡 PoC Available

Reflected XSS in oaskit's default HTML error handler · Advisory · lud/oaskit · GitHub

https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc

Vendor Advisories for CVE-2026-66296(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
oaskit0.1.0 ... 0.9.1 (23 versions)
  • 0.1.0 up to 0.14.1: fixed in 0.14.1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 59× 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 155 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66296?
CVE-2026-66296 is a medium vulnerability published on August 3, 2026. Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler. Oaskit.ErrorHandler.Default.formatreason/4 and Oaskit.ErrorHandler.Default.reasontohtml/1 in lib/oaskit/errorhandler/default.ex…
When was CVE-2026-66296 disclosed?
CVE-2026-66296 was first published on August 3, 2026, with the most recent update on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66296 actively exploited?
CVE-2026-66296 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (28th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66296?
CVE-2026-66296 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-66296?
A fix for CVE-2026-66296 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66296 are linked in the Vendor Advisories panel on this page.

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