# CVE-2026-45264: Nextcloud: ACL Rename Permission Bypass in Team Folders Allows Unauthorized File Renames

> Users with read and create permissions can rename files in team folders despite lacking update permissions, allowing unauthorized file modifications.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A: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:** 1 Jun 2026
- **Updated:** 1 Jun 2026
- **Also known as:** GHSA-wx2x-822r-rvmf

## What is CVE-2026-45264?

CVE-2026-45264 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 1 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nextcloud is an open source content collaboration platform. From versions 17.0.0 to before 17.0.15, 18.0.0 to before 18.1.12, 19.0.0 to before 19.1.16, 20.0.0 to before 20.1.11, and 21.0.0 to before 21.0.4, a user with READ and CREATE permission, but no UPDATE permission for a team folder can rename files in the team folder. This issue has been patched in versions 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-45264?


## How do I fix CVE-2026-45264?

No fix has been published for CVE-2026-45264 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45264 being exploited?

There is no known exploitation of CVE-2026-45264 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45264 and fix it if it is affected.

What it is: CVE-2026-45264 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 1 Jun 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-2026-45264 in the wild and no public exploit code.

Affected product: nextcloud security-advisories. 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-2026-45264/ (Markdown: https://insights.sbomify.com/CVE-2026-45264/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45264
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45264
- OSV: https://osv.dev/vulnerability/CVE-2026-45264

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45264/
Summaries are generated and may contain mistakes; the official description above is the record.