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Vulnerabilities

Security fix · CVE-2026-45159

Nextcloud is an open source content collaboration platform.

Published Jun 1, 2026 · catalog updated Jul 22, 2026

Severity
Low3.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.4%
Remediation
Advisory link
Affected products
See sources for product scope

Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able to also drop files into other end-to-end encrypted folders of the share owner. Reading and modifying of other files was not possible. This issue has been patched in versions 1.15.4, 1.16.3, 1.17.1, 1.18.1, and 2.0.0-rc.7.

Technical analysis

Mechanism and impact are interpreted from ingested advisories — not independent exploit research.

How to fix CVE-2026-45159

What to do

Three reads of the same public record: the decision, the versions on file, and the signals. Confirm the vendor advisory before you patch. This page does not publish exploit steps.

Executive

This is a public record, not a confirmed incident. CVE-2026-45159 is a low issue in the affected product (CVSS 3.5). CISA does not currently list it as known exploited. Next step: Compare installed versions with the linked vendor advisory before changing production.

System administrator

Check whether the affected product is installed. Affected ranges are not on this record yet. Compare installed versions with the linked vendor advisory before changing production.

Security analyst

CVSS 3.5. EPSS 0.4%. CISA does not currently list it as known exploited. Weaknesses: CWE-639. Sources: epss, nvd. Exploit links, when listed below, point at the original publisher.

Related intelligence

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 1, 2026 · NIST NVD

    Detected

    Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able to also drop files into other end-to-end encrypted folders of the share owner. Reading and modifying of other files was not possible. This is

  2. Jul 22, 2026 · NIST NVD

    Updated

    Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able to also drop files into other end-to-end encrypted folders of the share owner. Reading and modifying of other files was not possible. This is

Sources

  • FIRST EPSSExploitation probabilityCVE-2026-45159

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-45159

    Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able to also drop files in

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.