CVE-2025-66556

Name: CVE-2025-66556
Creator: NVD / NIST
Published: 2025-12-05T18:15:58.803+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.21%

Last modified Jun 17, 2026

CVE-2025-66556 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. Nextcloud talk is a video & audio conferencing app for Nextcloud. Prior to 20.1.8 and 21.1.2, a participant with chat permissions was able to delete poll drafts of other participants within the conversation based on their numeric ID. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

Description

Nextcloud talk is a video & audio conferencing app for Nextcloud. Prior to 20.1.8 and 21.1.2, a participant with chat permissions was able to delete poll drafts of other participants within the conversation based on their numeric ID. This vulnerability is fixed in 20.1.8 and 21.1.2.

Metrics

CVSS 3.1

4.3/10

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

EPSS Probability

0.21%

10.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-639

Affected Software

Vendor	Product	Versions
Nextcloud	Talk	>= 20.0.0, < 20.1.8
Nextcloud	Talk	>= 21.0.0, < 21.1.2

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-pr9f-vqgg-m2jhPatch, Vendor Advisory
https://github.com/nextcloud/spreed/commit/bd68e80d1dea98d84c1d621c2c681238cf041725Patch
https://github.com/nextcloud/spreed/pull/15532Issue Tracking, Patch
https://hackerone.com/reports/3247386Issue Tracking, Vendor Advisory

Timeline

Published: Dec 5, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-66556?

How severe is CVE-2025-66556?

CVE-2025-66556 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2025-66556?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-66556?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST