# CVE-2026-108740: GoatCounter through 2.7.0 Privilege Escalation via /user/pref Mass Assignment

> Logged-in users can escalate privileges to superuser by modifying protected fields via mass assignment in the user preference handler.

- **Severity:** High 7.2 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:H/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:** 11 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-4f43-5hgr-4m7r

## What is CVE-2026-108740?

CVE-2026-108740 is a high-severity vulnerability in arp242 GoatCounter, published on 11 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

GoatCounter through 2.7.0 contains a mass assignment privilege escalation vulnerability in the userPrefSave handler that allows logged-in users to modify protected account fields via form-encoded requests. Attackers with read-only access can POST user.access[all]=* and user.email_verified=true to /user/pref, bypassing readonly tags to gain superuser or admin access.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-108740?


## How do I fix CVE-2026-108740?

No fix has been published for CVE-2026-108740 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-108740 being exploited?

There is no known exploitation of CVE-2026-108740 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-108740 and fix it if it is affected.

What it is: CVE-2026-108740 is a high-severity vulnerability in arp242 GoatCounter, published on 11 Oct 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-2026-108740 in the wild and no public exploit code.

Affected product: arp242 GoatCounter. 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-2026-108740/ (Markdown: https://insights.sbomify.com/CVE-2026-108740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-108740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-108740
- OSV: https://osv.dev/vulnerability/CVE-2026-108740

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-108740/
Summaries are generated and may contain mistakes; the official description above is the record.