# CVE-2026-43621: Simple Machines Forum < 2.1.7 Authorization Confusion via Profile::load()

> Authenticated low-privileged users can gain administrator access and take over accounts by exploiting an authorization state-confusion in the profile loader.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/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:** 26 Aug 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-pw24-wq86-2799

## What is CVE-2026-43621?

CVE-2026-43621 is a high-severity authentication bypass vulnerability in SimpleMachines SMF, published on 26 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Simple Machines Forum (SMF) through 2.1.7, fixed in commit 6f0dc61, contains an authorization state-confusion vulnerability in the profile loader that allows authenticated low-privileged users to gain administrator access by supplying multiple values for the user parameter. Attackers can exploit the mismatch between Profile::$member and User::$me->is_owner during sequential profile loading to be treated as the owner of an administrator profile, enabling unauthorized password changes and full account takeover.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-43621?


## How do I fix CVE-2026-43621?

No fix has been published for CVE-2026-43621 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43621 being exploited?

There is no known exploitation of CVE-2026-43621 in the wild and no public exploit code.

Public exploit code:

- https://github.com/KharalDipendra/CVE-2026-43621 (github_poc): https://github.com/KharalDipendra/CVE-2026-43621

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43621 and fix it if it is affected.

What it is: CVE-2026-43621 is a high-severity authentication bypass vulnerability in SimpleMachines SMF, published on 26 Aug 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-2026-43621 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-2026-43621/ (Markdown: https://insights.sbomify.com/CVE-2026-43621/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43621
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43621
- OSV: https://osv.dev/vulnerability/CVE-2026-43621

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43621/
Summaries are generated and may contain mistakes; the official description above is the record.