CVE-2022-24838
Published: 11 April 2022
Summary
CVE-2022-24838 is a medium-severity Injection (CWE-74) vulnerability in Nextcloud Calendar. Its CVSS base score is 5.3 (Medium).
Operationally, ranked in the top 7.3% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Deeper analysis
Nextcloud Calendar, a calendar application within the Nextcloud framework, contains an SMTP command injection vulnerability in its appointment email handling. The flaw stems from insufficient sanitization of newlines and special characters in the email value supplied via JSON requests, which permits an attacker to terminate the intended RCPT TO command and inject arbitrary SMTP directives. The issue is tracked as CWE-74 and carries a CVSS 3.1 score of 5.3.
An unauthenticated remote attacker can exploit the weakness by crafting a malicious JSON payload that reaches the booking email workflow. Successful injection allows limited disclosure of information through manipulated SMTP sessions while leaving integrity and availability unaffected.
Advisories and patches from Nextcloud indicate that Calendar version 3.2.2 resolves the issue through proper input validation in the affected commit; no workarounds are available. The associated EPSS score has remained flat at 0.0878 with no material increase since disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2022-29623
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Developer assessments and testing (including injection-focused techniques) identify improper neutralization of special elements, and the verifiable flaw remediation corrects them pre-deployment.
Identifies indicators of injection attacks (command, SQL, LDAP, etc.) via anomaly and attack monitoring.