# CVE-2017-0894: Information disclosure in Nextcloud Server

> Attackers can access publicly shared calendars without valid tokens due to a logical error in Nextcloud Server.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 8 May 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-2c99-9fv7-72hj

## What is CVE-2017-0894?

CVE-2017-0894 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 8 May 2017. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Nextcloud Server before 11.0.3 is vulnerable to disclosure of valid share tokens for public calendars due to a logical error. Thus granting an attacker potentially access to publicly shared calendars without knowing the share token.

Weakness: CWE-863 (Incorrect Authorization), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2017-0894?

It affects 1 product.


Products: Nextcloud Nextcloud Server.

## How do I fix CVE-2017-0894?

No fix has been published for CVE-2017-0894 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-0894 being exploited?

There is no known exploitation of CVE-2017-0894 in the wild and no public exploit code.

## Other vulnerabilities in Nextcloud Nextcloud Server

- [CVE-2021-32802](https://insights.sbomify.com/CVE-2021-32802/): Preview generation used third-party library not suited for user-generated content in Nextcloud server (critical 9.3)
- [CVE-2023-26482](https://insights.sbomify.com/CVE-2023-26482/): Scope of workflow operations is not validated in nextcloud server (critical 9.1)
- [CVE-2018-3775](https://insights.sbomify.com/CVE-2018-3775/): Auth bypass in Nextcloud Server (high 8.8)
- [CVE-2023-35172](https://insights.sbomify.com/CVE-2023-35172/): Nextcloud Server password reset endpoint is not brute force protected (high 8.7)
- [CVE-2023-32320](https://insights.sbomify.com/CVE-2023-32320/): Nextcloud Server's brute force protection allows someone to send more requests than intended (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-0894 and fix it if it is affected.

What it is: CVE-2017-0894 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 8 May 2017. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2017-0894 in the wild and no public exploit code.

Affected product: Nextcloud Nextcloud Server. 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-2017-0894/ (Markdown: https://insights.sbomify.com/CVE-2017-0894/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-0894
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-0894
- OSV: https://osv.dev/vulnerability/CVE-2017-0894

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-0894/
Summaries are generated and may contain mistakes; the official description above is the record.