CVE-2026-13441 - The EventPrime – Events Calendar, Bookings and Tickets plugin for WordPress is vulnerable to Stored Cross-Site

CVE-2026-13441 + The EventPrime – Events Calendar, Bookings and Tickets plugin for WordPress is vulnerable to Stored Cross-Site + High + 2026-07-09

One-sentence business risk

Broken authentication or authorization can expose tenant data and administrator actions, which buyers treat as a release blocker.

Research notes

  • Root cause: The EventPrime – Events Calendar, Bookings and Tickets plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘new_event_type_background_color’ parameter in all versions up to, and including, 4.3.4.2 due to insufficient input sanitization an.
  • Affected versions: metagauss EventPrime – Events Calendar, Bookings and Tickets: 0 to < 4.3.4.2.
  • Fixed / safe versions: Vendor-fixed release or mitigation named by the upstream advisory.
  • Public exploit / PoC signal: the consulted NVD/GHSA/vendor sources describe the trigger class; treat it as reproducible until patched.
  • CVSS: 7.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.

Exact vulnerable code pattern

serve_uploaded_bytes(content_type=request.content_type)

Fixed / mitigated code pattern

sniff media, force an allowlisted image type, and set X-Content-Type-Options: nosniff

Dependency or runtime update:

composer show invoice-generator || true
composer require invoice-generator --with-all-dependencies
composer audit

Step-by-step integration guide

  1. Inventory invoice-generator across source, lockfiles, SBOMs, container images, CI images, and deployment manifests.
  2. Upgrade to Vendor-fixed release or mitigation named by the upstream advisory or apply the exact vendor patch referenced below.
  3. Replace the vulnerable xss pattern with the fixed pattern and fail closed on malformed input.
  4. Add a regression test that exercises the advisory trigger and proves the request is rejected, bounded, or authorized.
  5. Deploy through canary, monitor security logs and resource metrics, then remove temporary edge blocks only after all runtimes are fixed.

Alternative mitigations

  • Disable the vulnerable feature path while the package/runtime update rolls out.
  • Add WAF or reverse-proxy rules for traversal tokens, prototype-polluting keys, oversized frames, shell metacharacters, or unauthenticated tool calls matching the trigger class.
  • Restrict internal egress, rotate exposed secrets, and revoke affected tokens/keys if the vulnerability can disclose config, logs, JWT secrets, proxy credentials, or PKI material.
  • For admin/API authorization issues, temporarily require elevated roles and explicit ownership checks at the gateway.

Detection signature

id: cve-2026-13441-the-eventprime-events-calendar-bookings-and-tick
source: "MITRE CVE List V5"
dependency_or_product: "invoice-generator"
affected: "metagauss EventPrime \u2013 Events Calendar, Bookings and Tickets: 0 to < 4.3.4.2"
fixed: "Vendor-fixed release or mitigation named by the upstream advisory"
signals:
  - "xss"
  - "../"
  - "__proto__"
  - "tools/call"
  - "wp_ajax_nopriv"
  - "pickle.loads"
  - "shell command construction"
action: "upgrade, add regression test, and verify deploy artifact"

Copy-paste skill

You are remediating CVE-2026-13441 (The EventPrime – Events Calendar, Bookings and Tickets plugin for WordPress is vulnerable to Stored Cross-Site) in this repository.

Find every affected dependency, runtime, image, service configuration, and reachable code path. Upgrade or patch to Vendor-fixed release or mitigation named by the upstream advisory. Replace the vulnerable xss pattern with a fail-closed implementation, add a regression test for the trigger shape, and update deployment/SBOM artifacts. If this repository does not control the affected runtime, create TRIAGE.md naming the owner, affected version, fixed version, and blocking decision.

Keywords, affected tech stack, and revenue tags

  • Keywords: CVE-2026-13441, xss, invoice-generator, MITRE CVE List V5.
  • Affected tech stack: php/composer.
  • Revenue tags: sellable_to_fintech, enterprise_blocker, high_priority_sla.

References