Skip to main content

Simple Machines Forum EUVDEUVD-2026-42941

| CVE-2026-39903 HIGH
Incorrect Authorization (CWE-863)
2026-07-10 VulnCheck GHSA-62g6-4j9c-6v7p
Authentication Bypass PHP Smf
7.1
CVSS 4.0 · Vendor: VulnCheck
Share

Severity by source

Vendor (VulnCheck) PRIMARY
7.1 HIGH
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
vuln.today AI
7.6 HIGH

Network-reachable action needing only a low-priv authenticated account (PR:L) and no interaction; integrity high from unauthorized moderation, availability low from deletion, and C:L for enumeration of others' pending attachments.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

1
Analysis Generated
Jul 10, 2026 - 17:08 vuln.today

DescriptionCVE.org

Simple Machines Forum 2.1 prior to 2.1.8 and 3.0 prior to 3.0 Alpha 5 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.

AnalysisAI

Authorization bypass in Simple Machines Forum (SMF) 2.1 before 2.1.8 and 3.0 before 3.0 Alpha 5 lets any authenticated low-privileged member manipulate the attachment moderation queue without the required approve_posts permission. A single-character operator mistake in Sources/Actions/AttachmentApprove.php makes the permission check evaluate to true for everyone, so an ordinary user can approve, reject, or delete pending attachments on any board and enumerate other users' unapproved uploads. …

Unlock full vulnerability intelligence

  • Risk assessment & exploitation conditions
  • Attack chain visualization
  • Remediation with exact patch versions
  • Threat intelligence from 22 sources
  • Personal watchlist & email alerts
Continue with Google Continue with GitHub

Free forever · No credit card required

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Register or use existing low-priv account
Delivery
Log in and reach AttachmentApprove action
Exploit
Send approve/reject/delete request for pending attachments
Execution
Broken permission check passes unconditionally
Impact
Enumerate and delete or approve arbitrary attachments
Sign in to reveal

Vulnerability AssessmentAI

Exploitation Exploitation requires an authenticated low-privileged SMF account (PR:L) on an install running 2.1.x before 2.1.8 or 3.0 before 3.0 Alpha 5, and requires that the forum's attachment moderation queue is in use so that pending attachments exist to manipulate. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L) scores 7.1 High and aligns well with the description: network-reachable, low complexity, requires only a low-privileged authenticated account, no user interaction, primarily an integrity impact (unauthorized moderation actions) with limited availability impact (attachment deletion) and, per the vendor, no confidentiality impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario A registered forum member with no moderation rights logs in and sends the same HTTP request the attachment-approval action expects, targeting pending attachments on boards they do not moderate. Because the permission check always passes, they approve their own queued uploads to bypass moderation, or enumerate and delete other users' pending attachments across arbitrary boards. …
Remediation Upgrade to the fixed releases: Simple Machines Forum 2.1.8 for the 2.1 branch and 3.0 Alpha 5 for the 3.0 branch (Vendor-released patch: 2.1.8 / 3.0 Alpha 5), applying the upstream changes in SMF pull requests 9181 and 9182 (commits 7d048f8 and a7875e8). … Detailed patch versions, workarounds, and compensating controls in full report.
Sign in to read full assessment

Recommended ActionAI

Within 24 hours: Identify all Simple Machines Forum installations running SMF 2.1 versions prior to 2.1.8 or SMF 3.0 alpha releases prior to 3.0 Alpha 5, and document exposure scope. …

Sign in for detailed remediation steps and compensating controls.

Threat intelligence, references, and detailed analysis are available after sign-in.

More in PHP

View all
CVE-2012-1823 CRITICAL POC
9.8 May 11

sapi/cgi/cgi_main.c in PHP before 5.3.12 and 5.4.x before 5.4.2, when configured as a CGI script (aka php-cgi), does not
CVE-2016-1555 CRITICAL POC
9.8 Apr 21

(1) boardData102.php, (2) boardData103.php, (3) boardDataJP.php, (4) boardDataNA.php, and (5) boardDataWW.php in Netgear
CVE-2024-11680 CRITICAL POC
9.8 Nov 26

ProjectSend versions prior to r1720 are affected by an improper authentication vulnerability. Rated critical severity (C
CVE-2025-49113 CRITICAL POC
9.9 Jun 02

Roundcube Webmail contains a critical PHP object deserialization vulnerability (CVE-2025-49113, CVSS 9.9) that allows au
CVE-2017-9841 CRITICAL POC
9.8 Jun 27

Util/PHP/eval-stdin.php in PHPUnit before 4.8.28 and 5.x before 5.6.3 allows remote attackers to execute arbitrary PHP c
CVE-2025-0108 HIGH POC
8.8 Feb 12

Palo Alto Networks PAN-OS management web interface contains an authentication bypass allowing unauthenticated attackers

CVE-2021-25298 HIGH POC
8.8 Feb 15

Nagios XI version xi-5.7.5 is affected by OS command injection. Rated high severity (CVSS 8.8), this vulnerability is re
CVE-2021-25296 HIGH POC
8.8 Feb 15

Nagios XI version xi-5.7.5 is affected by OS command injection. Rated high severity (CVSS 8.8), this vulnerability is re
CVE-2013-4983 CRITICAL POC
10.0 Sep 10

The get_referers function in /opt/ws/bin/sblistpack in Sophos Web Appliance before 3.7.9.1 and 3.8 before 3.8.1.1 allows
CVE-2023-6553 CRITICAL POC
9.8 Dec 15

The Backup Migration plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 1
CVE-2024-46506 CRITICAL POC
10.0 May 13

NetAlertX (formerly PiAlert) versions 23.01.14 through 24.x before 24.10.12 allow unauthenticated command injection thro
CVE-2024-8353 CRITICAL POC
9.8 Sep 28

The GiveWP - Donation Plugin and Fundraising Platform plugin for WordPress is vulnerable to PHP Object Injection in all

Same weakness CWE-863 – Incorrect Authorization

View all
CVE-2025-54253 CRITICAL POC
10.0
CVE-2025-24200 MEDIUM
6.1
CVE-2025-21480 HIGH
8.6
CVE-2025-21479 HIGH
8.6
CVE-2017-4915 HIGH POC
7.8
CVE-2024-6782 CRITICAL POC
9.8
CVE-2024-38856 CRITICAL POC
9.8
CVE-2023-22518 CRITICAL POC
9.8

Same technique Authentication Bypass

View all
CVE-2023-22515 CRITICAL POC
9.8
CVE-2012-4681 CRITICAL POC
9.8
CVE-2013-2465 CRITICAL POC
9.8
CVE-2011-3544 CRITICAL POC
9.8
CVE-2012-1723 CRITICAL POC
9.8
CVE-2017-10271 HIGH POC
7.5
CVE-2015-1427 CRITICAL POC
9.8
CVE-2025-3248 CRITICAL POC
9.8

Share

EUVD-2026-42941 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy