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.
CVE-2026-39903
“—” beside the score: it is equal to the CVSS score beside it.
Score 7.1 from GitHub Security Advisory (severity: HIGH) published 2026-07-10. A secondary CVSS source baseline 7.1; sources differ by 0.0.
Also known asEUVD-2026-42941 (ENISA EUVD) · GHSA-62g6-4j9c-6v7p (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 7.1
- EG Score
- 7.1HIGHmedium confidence
- EG Risk
- 32EG Risk 32/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity71% × 45%Impact severity (EG Severity): CVSS 7.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.5% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule, then apply it. - EPSS PROB
- 0.5%
- EPSS %ILE
- 40th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.1): severity, escalated by confirmed exploitation. This CVE's 7.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule, then apply it.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
July 10, 2026
Last Modified
October 25, 2026
Advisory Details (5)
Auto-updated Jul 10, 2026Simple Machines Forum Authorization Bypass via AttachmentApprove.php | Advisories | VulnCheck
https://www.vulncheck.com/advisories/simple-machines-forum-authorization-bypass-via-attachmentapprove-php[2.1] Fixes a couple things with attachments and the image proxy
Fix merged in SimpleMachines/SMF PR #9182 on 2026-04-08 — awaiting tagged release
https://github.com/SimpleMachines/SMF/pull/9182[3.0] Fixes a couple things with attachments and the image proxy
Fix merged in SimpleMachines/SMF PR #9181 on 2026-04-08 — awaiting tagged release
https://github.com/SimpleMachines/SMF/pull/9181commit a7875e876a64 (SimpleMachines/SMF)
Fix landed in SimpleMachines/SMF commit a7875e876a64 — awaiting tagged release
https://github.com/SimpleMachines/SMF/commit/a7875e876a647572dd4c45da881b875092caac3dcommit 7d048f8d66aa (SimpleMachines/SMF)
Fix landed in SimpleMachines/SMF commit 7d048f8d66aa — awaiting tagged release
https://github.com/SimpleMachines/SMF/commit/7d048f8d66aab9af51cd6ee110fbad103cf673e8Vendor Advisories for CVE-2026-39903(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 44× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 99 of 252 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 153 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-27 20:58 UTCEG score recompute
- 2026-10-27 20:58 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-25 15:28 UTCEG score recompute
- 2026-10-25 15:27 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-10-25 14:31 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-24 00:06 UTCEG score recompute
- 2026-10-24 00:06 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-18 03:43 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-17 14:58 UTCEG score recompute
Show 74 moreShow fewer
- 2026-10-17 14:58 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-12 16:10 UTCEG score recompute
- 2026-10-11 19:52 UTCEG score recompute
- 2026-10-11 17:05 UTCEG score recompute
- 2026-10-11 14:32 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-01 15:11 UTCEG score recompute
- 2026-10-01 15:11 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-28 09:48 UTCEG score recompute
- 2026-09-28 09:48 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-24 11:13 UTCEG score recompute
- 2026-09-24 11:13 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-23 05:45 UTCEG score recompute
- 2026-09-23 05:45 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-18 05:19 UTCEG score recompute
- 2026-09-18 05:19 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-13 23:40 UTCEG score recompute
- 2026-09-13 23:40 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-13 08:12 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-12 16:06 UTCEG score recompute
- 2026-09-12 16:06 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-12 02:57 UTCEG score recompute
- 2026-09-12 02:57 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-08 02:54 UTCEG score recompute
- 2026-09-08 02:54 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-06 13:57 UTCEG score recompute
- 2026-09-06 13:57 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-05 21:45 UTCEG score recompute
- 2026-09-05 21:44 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-30 19:34 UTCEG score recompute
- 2026-08-30 19:34 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-30 06:25 UTCEG score recompute
- 2026-08-30 06:25 UTCGHSA enrichmentGHSA-62g6-4j9c-6v7p · GitHub severity HIGH · GitHub CVSS 7.1
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-27 21:41 UTCEG score recompute
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-39903?
When was CVE-2026-39903 made public?
Is CVE-2026-39903 actively exploited?
What is the CVSS score of CVE-2026-39903?
How do I remediate CVE-2026-39903?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-39903
Is Your Infrastructure Affected by CVE-2026-39903?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.