CVE-2026-45121

medium

EUVD alias: EUVD-2026-61053

Assigned by CNA: github_m

Published 2026-08-18 · Modified 2026-08-18

Discuss on Community Propose mitigation

CVSS v3

4.3

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

4.3

Description

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.

Predictions

Exploit likelihood

53%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

References

CWEs

CWE-863

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.