# CVE-2026-39903: Simple Machines Forum Authorization Bypass via AttachmentApprove.php

> Low-privileged users can bypass permission checks to approve, reject, or delete any pending attachments across all boards.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-62g6-4j9c-6v7p

## What is CVE-2026-39903?

CVE-2026-39903 is a high-severity missing authorization vulnerability in SimpleMachines SMF, published on 10 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-39903?


## How do I fix CVE-2026-39903?

No fix has been published for CVE-2026-39903 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39903 being exploited?

There is no known exploitation of CVE-2026-39903 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39903 and fix it if it is affected.

What it is: CVE-2026-39903 is a high-severity missing authorization vulnerability in SimpleMachines SMF, published on 10 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-39903 in the wild and no public exploit code.

Affected product: SimpleMachines SMF. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39903/ (Markdown: https://insights.sbomify.com/CVE-2026-39903/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39903
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39903
- OSV: https://osv.dev/vulnerability/CVE-2026-39903

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39903/
Summaries are generated and may contain mistakes; the official description above is the record.