CVE-2026-39903

HIGHPre-NVD 7.17.1—
EchelonGraph scoreHIGH confidence

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.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
7.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.1
EG Score
7.1(high)
EPSS
25.4%
KEV
Not listed

Published

July 10, 2026

Last Modified

July 14, 2026

Advisory Details (5)

Auto-updated Jul 10, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

Simple Machines Forum Authorization Bypass via AttachmentApprove.php | Advisories | VulnCheck

https://www.vulncheck.com/advisories/simple-machines-forum-authorization-bypass-via-attachmentapprove-php
github_pr

[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
github_pr

[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/9181
github_commit

commit a7875e876a64 (SimpleMachines/SMF)

Fix landed in SimpleMachines/SMF commit a7875e876a64 — awaiting tagged release

https://github.com/SimpleMachines/SMF/commit/a7875e876a647572dd4c45da881b875092caac3d
github_commit

commit 7d048f8d66aa (SimpleMachines/SMF)

Fix landed in SimpleMachines/SMF commit 7d048f8d66aa — awaiting tagged release

https://github.com/SimpleMachines/SMF/commit/7d048f8d66aab9af51cd6ee110fbad103cf673e8

Vendor 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 20× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-14 12:38 UTCEG score recompute
  2. 2026-07-14 12:38 UTCGHSA enrichment
  3. 2026-07-13 23:29 UTCEG score recompute
  4. 2026-07-13 23:29 UTCGHSA enrichment
  5. 2026-07-13 22:30 UTCEPSS rescore
  6. 2026-07-13 10:20 UTCEG score recompute
  7. 2026-07-13 10:20 UTCGHSA enrichment
  8. 2026-07-13 06:13 UTCEPSS rescore
  9. 2026-07-13 06:13 UTCEPSS rescore
  10. 2026-07-12 21:10 UTCEG score recompute
  11. 2026-07-12 21:10 UTCGHSA enrichment
  12. 2026-07-12 08:00 UTCEG score recompute
  13. 2026-07-12 08:00 UTCGHSA enrichment
  14. 2026-07-12 05:46 UTCEPSS rescore
  15. 2026-07-11 18:51 UTCEG score recompute
  16. 2026-07-11 18:51 UTCGHSA enrichment
  17. 2026-07-11 05:42 UTCEG score recompute
  18. 2026-07-11 05:42 UTCGHSA enrichment
  19. 2026-07-10 16:33 UTCEG score recompute
  20. 2026-07-10 16:32 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-39903?
CVE-2026-39903 is a high vulnerability published on July 10, 2026. 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…
When was CVE-2026-39903 disclosed?
CVE-2026-39903 was first published in the National Vulnerability Database on July 10, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39903 actively exploited?
CVE-2026-39903 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 25.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39903?
CVE-2026-39903 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-39903?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39903, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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