# CVE-2026-79990: GQL entry mutation `siteId` bypasses schema site scope, enabling cross-site content read/write/delete

> Attackers with limited site access can read, modify, or delete content in other sites via GraphQL mutations due to missing scope validation.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/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:** 2 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** GHSA-fvhj-675v-869c

## What is CVE-2026-79990?

CVE-2026-79990 is a high-severity missing authorization vulnerability in craftcms cms, published on 2 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Craft CMS GraphQL entry mutation resolvers (saveEntry, deleteEntry) read siteIddirectly from$argumentswithout passing throughArgumentManagerprepareArguments(), which is the function that enforces site-scope filtering via array_intersect against the GraphQL schema’s allowed sites. The query path (ElementResolverprepareElementQuery) correctly calls prepareArguments()`, so queries to unauthorized sites return empty. But mutations bypass this entirely — an attacker with a token scoped to Site A can create, modify, or delete entries in Site B by passing siteId in the mutations argument.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-79990?


## How do I fix CVE-2026-79990?

No fix has been published for CVE-2026-79990 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-79990 being exploited?

There is no known exploitation of CVE-2026-79990 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79990 and fix it if it is affected.

What it is: CVE-2026-79990 is a high-severity missing authorization vulnerability in craftcms cms, published on 2 Sep 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-2026-79990 in the wild and no public exploit code.

Affected product: craftcms cms. 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-2026-79990/ (Markdown: https://insights.sbomify.com/CVE-2026-79990/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79990
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79990
- OSV: https://osv.dev/vulnerability/CVE-2026-79990

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-79990/
Summaries are generated and may contain mistakes; the official description above is the record.