CVE-2026-27409Public exploitNetwork attack vector

Unauthenticated calendar sync disruption via token revocation

Published Jul 1, 2026 · Updated Jul 1, 2026

Missing authorization in Webba Booking 6.4.13 and earlier allows remote attackers to disconnect Google or Outlook calendar integrations. The handlers in includes/class_wbk_backend.php process calendar-revocation GET parameters and call clear_access_token() without verifying a request nonce. Exploitation requires a configured calendar integration and access to the WordPress administration route; successful requests remove OAuth tokens and stop synchronization without exposing booking data.

CVSS severity5.3
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Webba Booking 6.4.13 and earlier allows remote attackers to disconnect Google or Outlook calendar integrations. The handlers in includes/class_wbk_backend.php process calendar-revocation GET parameters and call clear_access_token() without verifying a request nonce. Exploitation requires a configured calendar integration and access to the WordPress administration route; successful requests remove OAuth tokens and stop synchronization without exposing booking data.

The record

CVE
CVE-2026-27409
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
Webba Appointment Booking
Product
Webba Booking
Classifications
CWE-862, CAPEC-180, T1489
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=6.4.13 changes=[{"at":"6.4.14","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Webba Appointment Booking · Webba Bookingversion=n/a <=6.4.13 changes=[{"at":"6.4.14","status":"unaffected"}]

Published CVSS scores

5.3PatchstackCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
CAPEC-180Exploiting Incorrectly Configured Access Control Security Levels
T1489Service Stop

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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