MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP Security Questions module does not validate the anti-CSRF token correctly, allowing same-site attackers to enable or disable registration challenge questions with a specially crafted URL. The controller processes GET requests for the disable and enable actions to modify mybb_questions.active without verifying the my_post_key token attached by the user interface. The uniquely identifying implementation details include admin/modules/config/questions.php. This issue is fixed in version 1.8.40.
CVE-2026-45126
This low-severity CVE scores 3.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 3.5
- EG Score
- 3.5(medium)
- EG Risk
- 16(Track)EG Risk 16/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity35% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 3%
- KEV
- Not listed
Published
August 18, 2026
Last Modified
August 18, 2026
References (4)
- security-advisories@githubhttps://github.com/mybb/mybb/commit/6893b395c7fa3b9e4de6235caea0ce198c376c4f
- security-advisories@githubhttps://github.com/mybb/mybb/releases/tag/mybb_1840
- security-advisories@githubhttps://github.com/mybb/mybb/security/advisories/GHSA-m42q-vgx3-fqcc
- security-advisories@githubhttps://mybb.com/versions/1.8.40
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 17× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-28 21:41 UTCEPSS rescore
- 2026-08-27 14:25 UTCEPSS rescore
- 2026-08-27 11:16 UTCEG score recompute
- 2026-08-26 14:46 UTCEPSS rescore
- 2026-08-25 13:49 UTCEPSS rescore
- 2026-08-24 13:39 UTCEG score recompute
- 2026-08-23 00:19 UTCEPSS rescore
- 2026-08-21 23:49 UTCEPSS rescore
- 2026-08-21 16:02 UTCEG score recompute
- 2026-08-20 22:55 UTCEPSS rescore
- 2026-08-19 17:04 UTCEPSS rescore
- 2026-08-18 18:24 UTCEG score recompute
- 2026-08-18 18:15 UTCEG score recompute
- 2026-08-18 16:30 UTCEG score recompute
- 2026-08-18 15:59 UTCEG score recompute
- 2026-08-18 15:59 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-45126?
When was CVE-2026-45126 disclosed?
Is CVE-2026-45126 actively exploited?
What is the CVSS score of CVE-2026-45126?
How do I remediate CVE-2026-45126?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-45126
Is Your Infrastructure Affected by CVE-2026-45126?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.