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TI-2026-28777 Aliases CVE-2026-39903GHSA-62g6-4j9c-6v7p

Simple Machines Forum Authorization Bypass via AttachmentApprove.php

Priority LOW 32CWE-863Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
None · High · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-863.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00467 40th percentileScored 2026-11-07
Fix Fixed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
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
SimpleMachinesSMF2.1.0 – 2.1.7; 3.0.0 and later—Patch availableCNA
  • SMF VendorSimpleMachines Affected 2.1.0 – 2.1.7; 3.0.0 and later Fixed in — 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:simplemachines:simple_machines_forum:*:*:*:*:*:*:*:*——SimpleMachines
  • cpe:2.3:a:simplemachines:simple_machines_forum:*:*:*:*:*:*:*:* Versions — — ·SimpleMachines

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-39903
  2. 2026-10-03 Alias added: GHSA-62g6-4j9c-6v7p

References

Patch 4

  • TI-2025-41147 A stored cross-site scripting (XSS) vulnerability in Simple Machines Forum v2.1.6 allows… CVSS 3.1MEDIUM 6.1
  • TI-2024-06892 SimpleMachines SMF User Alert Read Status index.php resource injection CVSS 4.0MEDIUM 5.3
  • TI-2024-06891 SimpleMachines SMF Delete User index.php resource injection CVSS 4.0MEDIUM 5.3
  • TI-2025-02251 SimpleMachines SMF ManageNews.php cross site scripting CVSS 4.0MEDIUM 5.1
  • TI-2025-02250 SimpleMachines SMF ManageAttachments.php cross site scripting CVSS 4.0MEDIUM 5.1
  • TI-2011-00980 SSI.php in Simple Machines Forum (SMF) before 1.1.13, and 2.x before 2.0 RC5, does not… CVSS 2.0HIGH 10.0
See all 33 →

Sources

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