CVE-2026-39903 Details
Description
Simple Machines Forum 2.1 prior to commit 7d048f8 and 3.0 prior to commit a7875e8 contains an authorization bypass vulnerability in Sources/Actions/AttachmentApprove.php where a single-character operator error causes the permission check to always pass regardless of user permissions. An authenticated low-privileged user can approve, reject, or delete any pending attachments on any board without holding the required approve_posts permission, bypass moderation queues for their own uploads, and enumerate and delete other users' pending attachments.
An authorization bypass vulnerability has been identified in Simple Machines Forum (SMF) versions 2.1 prior to 2.1.8 and 3.0 prior to 3.0 Alpha 5. The vulnerability resides in the AttachmentApprove.php file, where a single-character operator error in the permission check allows low-privileged authenticated users to approve, reject, or delete any pending attachments across all boards. This exploitation occurs without the necessary approve_posts permission, effectively bypassing moderation queues for their own uploads. Additionally, it enables users to enumerate and delete other users' pending attachments.
Users can update to Simple Machines Forum versions 2.1.8 or 3.0 Alpha 5 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 10, 2026CISA-ADP
Assessed Jul 14, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/SimpleMachines/SMF/commit/7d048f8d66aab9af51cd6ee110fbad103cf673e8 | [email protected] | Source CodeVendor |
| https://github.com/SimpleMachines/SMF/commit/a7875e876a647572dd4c45da881b875092caac3d | [email protected] | Source CodeVendor |
| https://github.com/SimpleMachines/SMF/pull/9181 | [email protected] | Issue TrackingVendor |
| https://github.com/SimpleMachines/SMF/pull/9182 | [email protected] | Issue TrackingVendor |
| https://www.vulncheck.com/advisories/simple-machines-forum-authorization-bypass-via-attachmentapprove-php | [email protected] | AdvisoryBundleRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-863 | Incorrect Authorization | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Simple Machines Forum | < 2.1.8 (semver) < 3.0.0 Alpha 5 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | CVE Modified | [email protected] |
| Jul 14, 2026 | CVE Modified | [email protected] |
| Jul 14, 2026 | CVE Modified | CISA-ADP |
| Jul 10, 2026 | New CVE Received | [email protected] |