How severe is CVE-2021-22906?

CVE-2021-22906 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-22906 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-22906?

CVE-2021-22906 affects Nextcloud End-to-end Encryption. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-22906?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-22906 published?

CVE-2021-22906 was published on 2021-06-11 and last updated on 2026-06-17.

CVE-2021-22906

CVE-2021-22906 is a medium-severity vulnerability in Nextcloud End-to-end Encryption with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-639
Affected product: Nextcloud End-to-end Encryption
Published: 2021-06-11
Last modified: 2026-06-17

Description

Nextcloud End-to-End Encryption before 1.5.3, 1.6.3 and 1.7.1 suffers from a denial of service vulnerability due to permitting any authenticated users to lock files of other users.

Frequently asked questions

What is CVE-2021-22906?: Nextcloud End-to-End Encryption before 1.5.3, 1.6.3 and 1.7.1 suffers from a denial of service vulnerability due to permitting any authenticated users to lock files of other users.
How severe is CVE-2021-22906?: CVE-2021-22906 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-22906 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-22906?: CVE-2021-22906 affects Nextcloud End-to-end Encryption. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-22906?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-22906 published?: CVE-2021-22906 was published on 2021-06-11 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nextcloud:end-to-end_encryption:*:*:*:*:*:*:*:*

More vulnerabilities in Nextcloud End-to-end Encryption

CVE-2023-35173 — Medium (CVSS 5.7): Nextcloud End-to-end encryption app provides all the necessary APIs to implement End-to-End encryption on the client…

All CVEs affecting Nextcloud End-to-end Encryption →

Other CWE-639 (Authorization Bypass Through User-Controlled Key (IDOR)) vulnerabilities

CVE-2025-40805 — Critical (CVSS 10.0): Affected devices do not properly enforce user authentication on specific API endpoints. This could facilitate an…
CVE-2024-45032 — Critical (CVSS 10.0): A vulnerability has been identified in Industrial Edge Management Pro (All versions < V1.9.5), Industrial Edge…
CVE-2026-34037 — Critical (CVSS 9.9): Coolify is an open-source and self-hostable tool for managing servers, applications, and databases. Prior to…
CVE-2026-52782 — Critical (CVSS 9.9): OpenProject is open-source, web-based project management software. Prior to 17.3.3 and 17.4.1, there is an IDOR through…
CVE-2026-45552 — Critical (CVSS 9.9): Roxy-WI is a web interface for managing Haproxy, Nginx, Apache and Keepalived servers. In versions 8.2.6.4 and prior,…
CVE-2026-29200 — Critical (CVSS 9.9): A critical IDOR vulnerability has been discovered in Comet Backup affecting all versions from 20.11.0 to 26.1.1 and…

Browse all CWE-639 (Authorization Bypass Through User-Controlled Key (IDOR)) vulnerabilities →