# Remediation Handoff: CVE-2026-66829

## Summary

NVD: 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 <meta http-equiv="refresh"> element... NVD: HtmlSanitizeEx.html5/1 keeps attacker-supplied <meta> elements in its output. NVD: 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.

## Why it matters

CVSS severity is LOW with score 2.3. EPSS percentile is 0.40356. KEV status is not listed in KEV. Use this as a defensive priority handoff, not as an execution instruction.

## Affected context

* Vendor: rrrene
* Product: htmlsanitizeex
* Component: unknown
* Version / CPE / PURL: unknown

## Remediation context

* Recommended route: vendor_patch_or_mitigation
* Vendor/advisory reference: official_reference_present
* Patch status: requires_confirmation
* Fixed version: unknown
* References: https://cna.erlef.org/cves/CVE-2026-66829.html, https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f, https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr, https://osv.dev/vulnerability/EEF-CVE-2026-66829

## Human checklist

* Confirm whether the listed product or package is present.
* Confirm affected version.
* Review vendor advisory or official source.
* Confirm patch, fixed version, mitigation, workaround, or monitor-only decision.
* Confirm exposure.
* Document remediation status.

## Safe AI / Codex handoff

* Goal: Prepare a defensive remediation plan for CVE-2026-66829 using only provided public-safe source context and any separate repo context supplied by the user.
* Allowed actions: summarize vendor guidance, prepare a defensive remediation plan, identify affected dependencies only when repo context is separately provided by the user, suggest tests and validation steps, document human verification questions
* Disallowed actions: generate offensive code, provide payloads, scan external targets, change production systems, merge or deploy changes, create GitHub issues or pull requests without explicit separate approval
* Acceptance criteria: Affected product or dependency presence is confirmed by a human., Affected version is confirmed or marked not applicable., Official advisory or source reference is reviewed., Patch, fixed version, mitigation, workaround, or monitor-only decision is documented., Validation steps are proposed without external scanning or production mutation.
* Human approval required: true

## Safety note

This handoff is for defensive triage and remediation planning only. It excludes offensive procedure, payload material, external target scan guidance, and auto-remediation.