# CVE-2018-3781: Cross-site scripting in nextcloud/talk

> Authenticated users can inject malicious scripts via unsanitized usernames in NextCloud Talk autocomplete, leading to stored XSS attacks against other users.

- **Severity:** Medium 5.4 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Aug 2018
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-86ww-pfxr-g767

## What is CVE-2018-3781?

CVE-2018-3781 is a medium-severity cross-site scripting vulnerability in nextcloud/talk, published on 13 Aug 2018. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A missing sanitization of search results for an autocomplete field in NextCloud Talk <3.2.5 could lead to a stored XSS requiring user-interaction. The missing sanitization only affected user names, hence malicious search results could only be crafted by authenticated users.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2018-3781?

It affects 1 product.


Products: Nextcloud Talk.

## How do I fix CVE-2018-3781?

No fix has been published for CVE-2018-3781 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-3781 being exploited?

There is no known exploitation of CVE-2018-3781 in the wild and no public exploit code.

## Other vulnerabilities in nextcloud/talk

- [CVE-2020-8180](https://insights.sbomify.com/CVE-2020-8180/): Code injection in Nextcloud Talk (critical 9.9)
- [CVE-2021-32689](https://insights.sbomify.com/CVE-2021-32689/): Nextcloud Talk not properly disassociating users from chats after account deletion (high 8.1)
- [CVE-2023-39957](https://insights.sbomify.com/CVE-2023-39957/): Path traversal allows tricking the Talk Android app into writing files into it's root directory (high 7.2)
- [CVE-2021-32676](https://insights.sbomify.com/CVE-2021-32676/): Session Fixation in Nextcloud Talk (medium 6.5)
- [CVE-2021-39222](https://insights.sbomify.com/CVE-2021-39222/): XSS in Talk (medium 6.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-3781 and fix it if it is affected.

What it is: CVE-2018-3781 is a medium-severity cross-site scripting vulnerability in nextcloud/talk, published on 13 Aug 2018. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2018-3781 in the wild and no public exploit code.

Affected product: nextcloud/talk. 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-2018-3781/ (Markdown: https://insights.sbomify.com/CVE-2018-3781/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-3781
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-3781
- OSV: https://osv.dev/vulnerability/CVE-2018-3781

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-3781/
Summaries are generated and may contain mistakes; the official description above is the record.