CVE-2026-45120 | BDVDB-2026-360832 Detail

mybbmybb

Description#

MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not verify private event status consistently, allowing users with viewing and moderation permissions to access and moderate private events. The private-event check used by get_events() in inc/functions_calendar.php and the event action is missing from the remaining calendar.php actions, despite the limited-access behavior described in inc/languages/english/calendar.lang.php. This issue is fixed in version 1.8.40.

Impact#

Per CVSS v3.1: confidentiality impact low, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-639 Authorization Bypass Through User-Controlled Key

References#

Exploit#

No public exploit known

History#

Version 12026-08-18Record published in the CVE List.

Published

Published: 2026-08-18
Last modified: 2026-08-18

Vendor information

Vendor: mybb
Product: mybb

All mybb vulnerabilities

Score

5.4 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 23.4.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Insecure Direct Object Reference

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 1.8.40
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

5.4 Medium

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

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	Low
Integrity	Low
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).