CVE-2026-66296

MEDIUMNVD 6.16.1—
EchelonGraph scoreHIGH 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 — 4 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%CVSS: 6.1Exploit: Elevated riskExposed: 0

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

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
6.1(high)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

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
github Patch Available🟡 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 rangeFixed inDependents
oaskit0.1.0 ... 0.9.1 (23 versions)0.14.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 52× 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. 2026-08-21 01:00 UTCEG score recompute
  2. 2026-08-21 01:00 UTCGHSA enrichment
  3. 2026-08-20 22:56 UTCEPSS rescore
  4. 2026-08-19 23:23 UTCEG score recompute
  5. 2026-08-19 23:23 UTCGHSA enrichment
  6. 2026-08-19 17:04 UTCEPSS rescore
  7. 2026-08-18 21:44 UTCEG score recompute
  8. 2026-08-18 21:44 UTCGHSA enrichment
  9. 2026-08-18 13:48 UTCEPSS rescore
  10. 2026-08-17 19:28 UTCEG score recompute▲ 1.00
  11. 2026-08-17 19:28 UTCGHSA enrichment
  12. 2026-08-17 19:27 UTCNVD updateCVSS v3 → 6.1
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-17 10:31 UTCEG score recompute
  15. 2026-08-17 10:31 UTCGHSA enrichment
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-16 08:53 UTCEG score recompute
  18. 2026-08-16 08:53 UTCGHSA enrichment
  19. 2026-08-15 07:15 UTCEG score recompute
  20. 2026-08-15 07:15 UTCGHSA enrichment
  21. 2026-08-15 01:30 UTCEPSS rescore
  22. 2026-08-14 05:37 UTCEG score recompute
  23. 2026-08-14 05:37 UTCGHSA enrichment
  24. 2026-08-13 22:00 UTCEPSS rescore
  25. 2026-08-13 03:59 UTCEG score recompute
Show 27 more
  1. 2026-08-13 03:59 UTCGHSA enrichment
  2. 2026-08-12 13:51 UTCEPSS rescore
  3. 2026-08-12 02:21 UTCEG score recompute
  4. 2026-08-12 02:21 UTCGHSA enrichment
  5. 2026-08-11 00:43 UTCEG score recompute
  6. 2026-08-11 00:43 UTCGHSA enrichment
  7. 2026-08-11 00:00 UTCEPSS rescore
  8. 2026-08-09 23:05 UTCEG score recompute
  9. 2026-08-09 23:05 UTCGHSA enrichment
  10. 2026-08-09 13:47 UTCEPSS rescore
  11. 2026-08-08 21:27 UTCGHSA enrichment
  12. 2026-08-07 19:49 UTCEG score recompute
  13. 2026-08-07 19:49 UTCGHSA enrichment
  14. 2026-08-06 18:11 UTCEG score recompute
  15. 2026-08-06 18:11 UTCGHSA enrichment
  16. 2026-08-06 13:47 UTCEPSS rescore
  17. 2026-08-05 19:17 UTCEPSS rescore
  18. 2026-08-05 19:17 UTCEPSS rescore
  19. 2026-08-05 16:33 UTCEG score recompute
  20. 2026-08-05 16:33 UTCGHSA enrichment
  21. 2026-08-04 15:10 UTCEPSS rescore
  22. 2026-08-04 14:53 UTCEG score recompute
  23. 2026-08-04 14:53 UTCGHSA enrichment
  24. 2026-08-03 20:19 UTCEG score recompute
  25. 2026-08-03 20:13 UTCEG score recompute
  26. 2026-08-03 19:38 UTCEG score recompute
  27. 2026-08-03 19:38 UTCMITRE cvelistV5first tracked

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 in the National Vulnerability Database 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% probability of exploitation in the next 30 days, which ranks it in the top 88.8% of all 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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66296, 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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