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TI-2026-32954 Aliases CVE-2026-45121

MyBB: Insufficient permission check for calendar select

Priority LOW 20CWE-863Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-863.

Summary

MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not check permissions consistently when listing calendars, allowing authenticated users to access titles of calendars that are otherwise inaccessible. The affected calendar-selection paths in calendar.php perform permission checks against an invalid calendar context before returning calendar titles. The uniquely identifying implementation details include titles of inaccessible calendars, and invalid calendar permission context. This issue is fixed in version 1.8.40.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00342 27th percentileScored 2026-11-08
Fix Fixed mybb (mybb): 1.8.40

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mybbmybbbefore 1.8.401.8.40Patch availableCNA
  • mybb Vendormybb Affected before 1.8.40 Fixed in 1.8.40 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*——mybb
  • cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:* Versions — — ·mybb

Remediation

  • Fix · CNA mybb (mybb) Fixed in 1.8.40

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45121

References

Other 4

  • TI-2011-04621 myBB 1.6.4 Backdoor Arbitrary Command Execution CVSS 4.0CRITICAL 10.0
  • TI-2022-08548 Remote code execution in mybb CVSS 3.1HIGH 7.2
  • TI-2021-22547 MyBB Timeline Plugin 1.0 Cross-Site Scripting and CSRF CVSS 4.0MEDIUM 6.9
  • TI-2023-21959 MyBB before 1.8.36 allows Code Injection by users with certain high privileges. CVSS 3.1HIGH 7.2
  • TI-2022-18641 Mail settings' command parameter injection in mybb CVSS 3.1HIGH 7.2
  • TI-2025-21092 An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the… CVSS 3.1HIGH 7.6
See all 173 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences