CVE-2026-39903

HIGH
MEDIUM Priority: 0.03 BB Relevance: 64/100
Published: 2026-07-10 Modified: 2026-10-25 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Interaction Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: None
S: X
AT: None
VC: None
VI: High
VA: Low

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.

Weakness Classification (1)

Bug Bounty Relevance

64 / 100
✓ Network accessible
✓ Low complexity
✓ No user interaction

CVSS Score

7.1 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.47%
Raw Score 0.004670
Percentile 40.4%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00467
2026-10-28
0.00467

Intelligence Sources

nvd ref →