CVE-2021-22896

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-11 · updated 2026-06-17
Weakness: CWE-862

Description

Nextcloud Mail before 1.9.5 suffers from improper access control due to a missing permission check allowing other authenticated users to create mail aliases for other users.

Affected products

com.nextcloud.client: before 1.9.5 — fixed in 1.9.5

How to fix

Upgrade to a fixed version: com.nextcloud.client 1.9.5. Check the vendor advisory for mitigations.

References

https://github.com/nextcloud/mail/pull/4864
https://github.com/nextcloud/mail/releases/tag/v1.9.5
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jmgp-77jq-fjp3
https://hackerone.com/reports/1129996
https://github.com/nextcloud/mail/pull/4864
https://github.com/nextcloud/mail/releases/tag/v1.9.5
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jmgp-77jq-fjp3
https://hackerone.com/reports/1129996

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