CVE-2022-24838Network attack vector

SMTP command injection via unvalidated booking email

Published Apr 11, 2022 · Updated Apr 23, 2025

SMTP command injection in Nextcloud Calendar before 3.2.2 allows remote attackers to inject arbitrary SMTP commands through appointment emails. The bookSlot method in BookingController accepts the JSON email value without validating or neutralizing newline characters before it is used in an SMTP RCPT TO command. An exposed appointment-booking form is sufficient; injected CRLF sequences terminate the recipient command and add attacker-chosen SMTP commands.

CVSS severity5.3
Medium
EPSS probability33.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

SMTP command injection in Nextcloud Calendar before 3.2.2 allows remote attackers to inject arbitrary SMTP commands through appointment emails. The bookSlot method in BookingController accepts the JSON email value without validating or neutralizing newline characters before it is used in an SMTP RCPT TO command. An exposed appointment-booking form is sufficient; injected CRLF sequences terminate the recipient command and add attacker-chosen SMTP commands.

The record

CVE
CVE-2022-24838
Published
Apr 11, 2022
Updated
Apr 23, 2025
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-93
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=< 3.2.2

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo