CVE-2026-45543

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.

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CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0027

Probability of exploitation

0.18%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-552 CWE-552

Affected Products

Vendor	Product	Versions
nextcloud	forms	4.3.0 — 5.2.7

References

Advisories & Patches

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

Other References

https://hackerone.com/reports/3617352

Frequently Asked Questions

What is CVE-2026-45543? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-45543? +

CVE-2026-45543 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0027, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-45543? +

CVE-2026-45543 affects products from nextcloud, specifically: forms. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-45543? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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