# CVE-2026-77166: Business logic in Collectives

> Attackers can break the sidebar layout by injecting long text into the emoji field, potentially hiding other interface items.

- **Severity:** Low 2.4 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** GHSA-8gq2-j3j2-95vm

## What is CVE-2026-77166?

CVE-2026-77166 is a low-severity vulnerability in Nextcloud Collectives, published on 21 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

The emoji field in the page emoji update endpoint does not properly validate user input. By injecting long text and line breaks, the sidebar layout becomes broken and can hide other items.

Weakness: CWE-840

## Which versions are affected by CVE-2026-77166?


## How do I fix CVE-2026-77166?

No fix has been published for CVE-2026-77166 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-77166 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77166 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77166 and fix it if it is affected.

What it is: CVE-2026-77166 is a low-severity vulnerability in Nextcloud Collectives, published on 21 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77166 exists.

Affected product: Nextcloud Collectives. 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-2026-77166/ (Markdown: https://insights.sbomify.com/CVE-2026-77166/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77166
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77166
- OSV: https://osv.dev/vulnerability/CVE-2026-77166

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77166/
Summaries are generated and may contain mistakes; the official description above is the record.