CVE-2026-105193 Booking Calendar CVE debrief

Who should care

Defenders responsible for WordPress installations using the Booking Calendar plugin, particularly those with public-facing booking systems, should assess exposure and take action to protect against potential unauthorized access or modification of booking information.

Why it matters

CVE-2026-105193 is a vulnerability in the Booking Calendar WordPress plugin that allows unauthenticated attackers to predict booking hashes and access or modify booking information. Defenders should prioritize verifying and updating Booking Calendar installations, assessing exposure, and implementing compensating controls to protect against potential unauthorized access or modification of booking information.

• Potential unauthorized access to sensitive booking information
• Possible modification of booking details by unauthenticated attackers
• Need for verification and updates to Booking Calendar installations
• Potential impact on data integrity and confidentiality

Technical summary

The Booking Calendar WordPress plugin before 11.8 generates per-booking access hashes with low entropy, allowing unauthenticated attackers to predict hashes and access or modify booking information. The plugin's use of time-seeded values for generating hashes can be exploited by attackers who can determine a booking's creation time. This vulnerability affects WordPress installations using the Booking Calendar plugin, particularly those with public-facing booking systems. Defenders should prioritize verifying and updating Booking Calendar installations to version 11.8 or later, assessing exposure, and implementing compensating controls to protect against potential unauthorized access or modification of booking

Defensive priority

Defenders should prioritize verifying and updating Booking Calendar installations to version 11.8 or later, assessing exposure, and implementing compensating controls to protect against potential unauthorized access or modification of booking information.

Recommended defensive actions

• Verify and update Booking Calendar installations to version 11.8 or later
• Assess exposure and implement compensating controls to protect against potential unauthorized access or modification of booking information
• Monitor for suspicious activity related to booking hashes and unauthorized access attempts
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description and affected versions. However, additional information from other sources may be necessary to fully assess the vulnerability and its potential impact.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.