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TI-2026-32958 Aliases CVE-2026-45125

MyBB: Email User CRLF injection

Priority LOW 30CWE-93Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00412 35th percentileScored 2026-11-07
Fix Fixed mybb (mybb): 1.8.40

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mybbmybbbefore 1.8.401.8.40Patch availableCNA
  • mybb Vendormybb Affected before 1.8.40 Fixed in 1.8.40 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*——mybb
  • cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:* Versions — — ·mybb

Remediation

  • Fix · CNA mybb (mybb) Fixed in 1.8.40

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45125

References

Other 4

  • TI-2011-04621 myBB 1.6.4 Backdoor Arbitrary Command Execution CVSS 4.0CRITICAL 10.0
  • TI-2022-08548 Remote code execution in mybb CVSS 3.1HIGH 7.2
  • TI-2021-22547 MyBB Timeline Plugin 1.0 Cross-Site Scripting and CSRF CVSS 4.0MEDIUM 6.9
  • TI-2023-21959 MyBB before 1.8.36 allows Code Injection by users with certain high privileges. CVSS 3.1HIGH 7.2
  • TI-2022-18641 Mail settings' command parameter injection in mybb CVSS 3.1HIGH 7.2
  • TI-2025-21092 An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the… CVSS 3.1HIGH 7.6
See all 173 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences