What’s Vulnerable › Vulnerabilities

CVE-2022-24838: Command Injection in Appointment Emails for Nextcloud Calendar

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 33.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-04-11 · updated 2026-06-17
• Weakness: CWE-74

Description

Nextcloud Calendar is a calendar application for the nextcloud framework. SMTP Command Injection in Appointment Emails via Newlines: as newlines and special characters are not sanitized in the email value in the JSON request, a malicious attacker can inject newlines to break out of the `RCPT TO:<BOOKING USER'S EMAIL> ` SMTP command and begin injecting arbitrary SMTP commands. It is recommended that Calendar is upgraded to 3.2.2. There are no workaround available.

Affected products

• Nextcloud Calendar application: before 3.2.2 — fixed in 3.2.2

How to fix

Upgrade to a fixed version: Nextcloud Calendar application 3.2.2. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/calendar/commit/7b70edfb8a0fcf0926f613ababcbd56c6ecd9f35
• https://github.com/nextcloud/calendar/pull/4073
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-8xv5-4855-24qf
• https://github.com/nextcloud/calendar/commit/7b70edfb8a0fcf0926f613ababcbd56c6ecd9f35
• https://github.com/nextcloud/calendar/pull/4073
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-8xv5-4855-24qf

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