CVE-2026-46482

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 75% 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).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Impact

The registration component does not validate the text-based _Security Question_ CAPTCHA correctly, allowing attackers to bypass the challenge via a specially crafted value.

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

Details

The public _Registration_ workflow (member.php?action=do_register) accepts a hidden field question_id — expected to match the question session identifier (mybb_questionsessions.sid) — and validates the challenge answer without a fail-closed fallback for invalid identifiers. If the value is blank, forged, or expired, the request continues without a question-related error.

Patches

MyBB 1.8.(...) resolves this issue with the following changes:
  • Commit: https://github.com/mybb/mybb/commit/
  • .patch: https://github.com/mybb/mybb/commit/.patch

References

  • Release Notes: https://mybb.com/versions/1.8.(...)/

For more information

Go to mybb.com/security to report possible security concerns or to learn more about security research at MyBB.

Contact

The security team can be reached at [email protected].

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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 computed
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
25%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 18, 2026

Advisory Details (4)

Auto-updated Aug 18, 2026
Patch available. Sources: github, github_commit, github_release.
generic

Version 1.8.40 - MyBB

https://mybb.com/versions/1.8.40
github_release Patch Available

mybb_1840

Patch available: mybb/mybb mybb_1840

https://github.com/mybb/mybb/releases/tag/mybb_1840
github_commit Patch Available

commit bd2a3447939d (mybb/mybb)

Patch available: mybb/mybb mybb_1840 (contains commit bd2a3447939d)

https://github.com/mybb/mybb/commit/bd2a3447939d3084a5926dd66ece04649e0e0d60
github Patch Available

Security Question insufficient validation · Advisory · mybb/mybb · GitHub

https://github.com/mybb/mybb/security/advisories/GHSA-v2h7-4jp7-j6hh

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 16× 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.

  1. 2026-08-25 20:38 UTCEG score recompute
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 20:13 UTCEG score recompute
  4. 2026-08-23 19:55 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-22 19:37 UTCEG score recompute
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-21 19:19 UTCEG score recompute
  9. 2026-08-20 22:55 UTCEPSS rescore
  10. 2026-08-19 18:43 UTCEG score recompute
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 18:24 UTCEG score recompute
  13. 2026-08-18 18:00 UTCEG score recompute
  14. 2026-08-18 16:30 UTCEG score recompute
  15. 2026-08-18 15:59 UTCEG score recompute
  16. 2026-08-18 15:59 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-46482?
CVE-2026-46482 is a medium vulnerability published on August 18, 2026. Impact The registration component does not validate the text-based Security Question CAPTCHA correctly, allowing attackers to bypass the challenge via a specially crafted value. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Details The public Registration workflow (member.php?action=doregister)…
When was CVE-2026-46482 disclosed?
CVE-2026-46482 was first published in the National Vulnerability Database on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-46482 actively exploited?
CVE-2026-46482 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 74.8% of all scored CVEs.
What is the CVSS score of CVE-2026-46482?
CVE-2026-46482 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-46482?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-46482, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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