phpMyFAQ: Stored XSS via Regex Bypass in Filter::removeAttributes()

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.1 · CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N

EPSS

• CVE-2026-34729: 0.25% estimated exploitation activity in the next 30 days; percentile 16.50 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The sanitization pipeline for FAQ content is: 1. Filter::filterVar($input, FILTERSANITIZESPECIALCHARS) — encodes <, , ", ', & to HTML entities 2. htmlentitydecode($input, ENTQUOTES | ENTHTML5) — decodes entities back to characters 3. Filter::removeAttributes($input) — removes dangerous HTML attributes The removeAttributes() regex at line 174 only matches attributes with double-quoted values: This regex does NOT match: - Attributes with single quotes: onerror='alert(1)' - Attributes without quotes: onerror=alert(1) An attacker can bypass sanitization by submitting FAQ content with unquoted or single-quoted event handler attributes. Details Affected File: phpmyfaq/src/phpMyFAQ/Filter.php, line 174 Sanitization flow for FAQ question field: FaqController::create() lines 110, 145-149: Template rendering: faq.twig line 36: How the bypass works: 1. Attacker submits: <img src=x onerror=alert(1) 2. After FILTERSANITIZESPECIALCHARS: &lt;img src=x onerror=alert(1)&gt; 3. After…

Published by the source

1 Apr 2026, 22:31 UTC

Last modified by the source

6 Apr 2026, 17:18 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cv2g-8cj8-vgc7

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# Patch Next advisory brief: CVE-2026-34729

Advisory: phpMyFAQ: Stored XSS via Regex Bypass in Filter::removeAttributes()
IDs: CVE-2026-34729, GHSA-cv2g-8cj8-vgc7
Record: https://patchnext.com/advisories/cve-2026-34729 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: phpmyfaq/phpmyfaq 4.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist phpmyfaq/phpmyfaq: affected <= 4.1.0; fixed in 4.1.1

## Suggested inspection (read-only)
- Packagist phpmyfaq/phpmyfaq: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on phpmyfaq/phpmyfaq.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cv2g-8cj8-vgc7 (GitHub-reviewed advisory GHSA-cv2g-8cj8-vgc7 lists affected ranges: Packagist phpmyfaq/phpmyfaq >=0 <=4.1.0)

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