High 7.1Published Jul 10, 2026

CVE-2026-39903Simple Machines Forum Authorization Bypass via AttachmentApprove.php

Updated under an hour ago (Oct 28, 2026, 12:00 AM ET)

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It affects SimpleMachines SMF. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for SimpleMachines SMF

Exploited in the last 30 days

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.

CVSS: 7.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Jul 27, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

SimpleMachines SMF simplemachines:smf (from the name)	from 2.1.0 through 2.1.7; 7d048f8d66aab9af51cd6ee110fbad103cf673e8 not affected; 3.0.0; a7875e876a647572dd4c45da881b875092caac3d not affected	CNA record

References

References

https://github.com/SimpleMachines/SMF/pull/9182	issue-tracking
https://github.com/SimpleMachines/SMF/pull/9181	issue-tracking
https://github.com/SimpleMachines/SMF/commit/7d048f8d66aab9af51cd6ee110fbad103cf673e8	patch
https://github.com/SimpleMachines/SMF/commit/a7875e876a647572dd4c45da881b875092caac3d	patch
https://www.vulncheck.com/advisories/simple-machines-forum-authorization-bypass-via-attachmentapprove-php	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.