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Authorization Bypass (IDOR)Weakness · CWE-639

CVE-2026-9188

MEDIUM · 5.3 CVSS v3.1 Published 2026-07-02
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 7 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The Appointment Bookings for Zoom GoogleMeet and more – Wappointment plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to and including 2.7.6 via the `appointmentkey` parameter due to the appointment `edit_key` — the sole authorization token consumed by `tryCancel()` — being generated as a predictable, unsalted MD5 hash of only `client_id` (a sequential integer), `start_at` (a publicly observable appointment timestamp), and `staff_id` (a small enumerable integer), with no secret salt or random component, and the unauthenticated cancellation and rescheduling REST endpoints performing no ownership or identity verification beyond matching this reconstructible key. This makes it possible for unauthenticated attackers to compute valid `edit_key` values for appointments belonging to other users and cancel or reschedule those appointments arbitrarily. Exploitation requires the `allow_cancellation` or `allow_rescheduling` setting to be enabled on the site, both of which are common configurations for active booking deployments; an attacker can obtain the inputs needed to reconstruct a victim's key by booking their own appointment to observe their sequential `client_id` and correlating publicly visible appointment times and enumerable staff identifiers.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Wappointment WordPress plugin up to 2.7.6 uses a predictable edit_key (unsalted MD5 hash of client_id, start_at, and staff_id) to authorize appointment cancellation and rescheduling via unauthenticated REST endpoints. Attackers can reconstruct valid keys by booking their own appointment to discover their sequential client_id, then computing MD5 hashes for other users' appointments using publicly observable timestamps and enumerable staff IDs.

MitigationDisable the allow_cancellation and allow_rescheduling settings until a patched version is available; otherwise, implement proper ownership verification and replace the predictable edit_key with a cryptographically random token.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Wappointment plugin version
    Check the installed Wappointment plugin version in WordPress (wp-admin > Plugins or via WP-CLI: wp plugin list --name=wappointment). Compare the version number to 2.7.6.
    Affected if The installed version is 2.7.6 or lower.
  2. Confirm plugin is active
    Check if the Wappointment plugin is currently active on the WordPress site.
    Affected if The plugin is active and running a vulnerable version.
  3. Inspect cancellation/rescheduling settings
    Navigate to Wappointment settings in WordPress admin (typically under Wappointment > Settings or Appointments). Look for options labeled 'allow_cancellation' and 'allow_rescheduling'.
    Affected if Either allow_cancellation or allow_rescheduling is enabled (set to 'yes', 'true', or '1').
  4. Test unauthenticated REST endpoint accessibility
    Send a direct HTTP request to the appointment cancellation/rescheduling endpoints without providing authentication credentials. Example: curl -X POST https://your-site.com/wp-json/wappointment/v1/appointment/cancel -H 'Content-Type: application/json' -d '{"appointment_id":"123"}'.
    Affected if The endpoint accepts requests without requiring authentication or valid session.
  5. Verify edit_key implementation
    Examine the plugin source code (if accessible) for the function that generates the edit_key. Look for MD5 hash usage combined with client_id, start_at, and staff_id values.
    Affected if The edit_key is generated using unsalted MD5 hash of predictable values (client_id, start_at, staff_id) rather than a cryptographically random token.

A user is affected if Wappointment version 2.7.6 or lower is active AND either allow_cancellation or allow_rescheduling is enabled, allowing unauthenticated actors to manipulate appointments using predictably constructed edit_keys.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable the allow_cancellation and allow_rescheduling settings until a patched version is available; otherwise, implement proper ownership verification and replace the predictable edit_key with a cryptographically random token.

Recommended fix High confidence

Version 2.7.7 or later

  1. 1. Log in to the WordPress admin dashboard
  2. 2. Navigate to Plugins > Installed Plugins
  3. 3. Locate the 'Appointment Bookings for Zoom GoogleMeet and more – Wappointment' plugin
  4. 4. Check the current installed version number
  5. 5. If the installed version is 2.7.6 or earlier, click 'Update Now' to upgrade to the latest version
  6. 6. Alternatively, navigate to Dashboard > Updates and apply available updates
  7. 7. After updating, verify the new version number is 2.7.7 or later

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-9188 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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