CVE-2026-45119
MyBB: ACP UTF-8 Conversion CSRF
MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
MyBB: ACP UTF-8 Conversion CSRF
MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
- Record
CVE-2026-45119- CVSS 3.1
- 4.6 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L - Weakness
- CWE-352
- Updated
- 2026-11-02
EUVDEUVD-2026-61009
MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
- Record
EUVD-2026-61009- CVSS 3.1
- 4.6 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L - Updated
- 2026-11-02
NVD
MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
- Record
CVE-2026-45119- CVSS 3.1
- 4.6 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L - Weakness
- CWE-352
- Updated
- 2026-11-02
OSV
MyBB: ACP UTF-8 Conversion CSRF
MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
- Record
CVE-2026-45119- CVSS 3.1
- 4.6 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L - Weakness
- CWE-352
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-45119 is a medium vulnerability (CVSS 4.6) in Mybb, published August 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.17%, the 6th percentile. No source names a fixed version.
References
github.com/mybb/mybb/security/advisories/GHSA-p48q-4vgf-q7x8
mybb.com/versions/1.8.40
nvd.nist.gov/vuln/detail/CVE-2026-45119