MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?action=do_emailuser accepts the fromname HTTP parameter for guests or the stored username for authenticated users when the cansendemail group permission is enabled. When mail_handler is set to the default PHP mail value, the sender name is used without sanitization in Return-Path and Reply-To headers, allowing arbitrary headers to be injected with CRLF sequences. This issue is fixed in version 1.8.40.
Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Tue, 18 Aug 2026 18:30:00 +0000
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Tue, 18 Aug 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
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| Description | MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?action=do_emailuser accepts the fromname HTTP parameter for guests or the stored username for authenticated users when the cansendemail group permission is enabled. When mail_handler is set to the default PHP mail value, the sender name is used without sanitization in Return-Path and Reply-To headers, allowing arbitrary headers to be injected with CRLF sequences. This issue is fixed in version 1.8.40. | |
| Title | MyBB: Email User CRLF injection | |
| Weaknesses | CWE-93 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-08-18T17:46:25.763Z
Reserved: 2026-05-08T20:08:17.208Z
Link: CVE-2026-45125
No data.
Status : Received
Published: 2026-08-18T16:17:07.667
Modified: 2026-08-18T18:17:36.450
Link: CVE-2026-45125
No data.
OpenCVE Enrichment
Updated: 2026-08-18T18:15:04Z
Weaknesses