How severe is CVE-2021-32727?

CVE-2021-32727 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-32727 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-2021-32727?

CVE-2021-32727 affects Nextcloud. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-32727?

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

When was CVE-2021-32727 published?

CVE-2021-32727 was published on 2021-07-12 and last updated on 2026-06-17.

CVE-2021-32727

CVE-2021-32727 is a medium-severity vulnerability in Nextcloud with a CVSS 3.x base score of 5.7. 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-295.

Key facts

Severity: Medium (CVSS 3.x base score 5.7)
CVSS v2: 5.0
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Nextcloud
Published: 2021-07-12
Last modified: 2026-06-17

Description

Nextcloud Android Client is the Android client for Nextcloud. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.16.1, the Nextcloud Android client skipped a step that involved the client checking if a private key belonged to a previously downloaded public certificate. If the Nextcloud instance served a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. The vulnerability is patched in version 3.16.1. As a workaround, do not add additional end-to-end encrypted devices to a user account.

Frequently asked questions

What is CVE-2021-32727?: Nextcloud Android Client is the Android client for Nextcloud. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.16.1, the Nextcloud Android client skipped a step that involved the client checking if a private key belonged to a previously downloaded public certificate. If the Nextcloud instance served a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. The vulnerability is patched in version 3.16.1. As a workaround, do not add additional end-to-end encrypted devices to a user account.
How severe is CVE-2021-32727?: CVE-2021-32727 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-32727 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-2021-32727?: CVE-2021-32727 affects Nextcloud. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-32727?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-32727 published?: CVE-2021-32727 was published on 2021-07-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nextcloud:nextcloud:*:*:*:*:*:android:*:*

More vulnerabilities in Nextcloud

CVE-2019-5454 — Critical (CVSS 9.8): SQL Injection in the Nextcloud Android app prior to version 3.0.0 allows to destroy a local cache when a harmful query…
CVE-2021-43863 — High (CVSS 7.5): The Nextcloud Android app is the Android client for Nextcloud, a self-hosted productivity platform. The Nextcloud…
CVE-2023-28999 — Medium (CVSS 6.9): Nextcloud is an open-source productivity platform. In Nextcloud Desktop client 3.0.0 until 3.8.0, Nextcloud Android app…
CVE-2019-5455 — Medium (CVSS 6.8): Bypassing lock protection exists in Nextcloud Android app 3.6.0 when creating a multi-account and aborting the process.
CVE-2019-5450 — Medium (CVSS 6.8): Improper sanitization of HTML in directory names in the Nextcloud Android app prior to version 3.7.0 allowed to style…
CVE-2021-22912 — Medium (CVSS 6.5): Nextcloud iOS before 3.4.2 suffers from an information disclosure vulnerability when searches for sharees utilize the…

All CVEs affecting Nextcloud →

Other CWE-295 (Improper Certificate Validation) vulnerabilities

CVE-2026-4370 — Critical (CVSS 10.0): A vulnerability was identified in Juju from version 3.2.0 until 3.6.19 and from version 4.0 until 4.0.4, where the…
CVE-2026-30836 — Critical (CVSS 10.0): Step CA is an online certificate authority for secure, automated certificate management for DevOps. Versions 0.30.0-rc6…
CVE-2025-68121 — Critical (CVSS 10.0): During session resumption in crypto/tls, if the underlying Config has its ClientCAs or RootCAs fields mutated between…
CVE-2022-20703 — Critical (CVSS 10.0): Multiple vulnerabilities in Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers could allow an attacker…
CVE-2021-1471 — Critical (CVSS 9.9): Multiple vulnerabilities in Cisco Jabber for Windows, Cisco Jabber for MacOS, and Cisco Jabber for mobile platforms…
CVE-2026-20184 — Critical (CVSS 9.8): A vulnerability in the integration of single sign-on (SSO) with Control Hub in Cisco Webex Services could have allowed…

Browse all CWE-295 (Improper Certificate Validation) vulnerabilities →