Nextcloud Talk up to 20.1.7/21.1.1 Conversation authorization

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Nextcloud Talk up to 20.1.7/21.1.1. The affected element is an unknown function of the component Conversation Handler. The manipulation results in authorization. This vulnerability is known as CVE-2025-66556. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Nextcloud Talk up to 20.1.7/21.1.1. Affected is some unknown functionality of the component Conversation Handler. The manipulation with an unknown input leads to a authorization vulnerability. CWE is classifying the issue as CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. This is going to have an impact on integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2025-66556 since 12/04/2025. The exploitability is told to be easy. It is possible to launch the attack remotely. There are neither technical details nor an exploit publicly available.

Upgrading to version 20.1.8 or 21.1.2 eliminates this vulnerability. Applying the patch bd68e80d1dea98d84c1d621c2c681238cf041725 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-2757). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Nextcloud Nextcloud

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.3

VulDB Base Score: 5.4
VulDB Temp Score: 5.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.3
NVD Vector: 🔒

CNA Base Score: 3.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Authorization
CWE: CWE-639 / CWE-285 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Talk 20.1.8/21.1.2
Patch: bd68e80d1dea98d84c1d621c2c681238cf041725

Timelineinfo

12/04/2025 CVE reserved
12/06/2025 +2 days Advisory disclosed
12/06/2025 +0 days VulDB entry created
12/09/2025 +3 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-pr9f-vqgg-m2jh
Status: Confirmed

CVE: CVE-2025-66556 (🔒)
GCVE (CVE): GCVE-0-2025-66556
GCVE (VulDB): GCVE-100-334560
CERT Bund: WID-SEC-2025-2757 - Nextcloud (Contacts, Talk, Deck und Twofactor WebAuthn): Mehrere Schwachstellen

Entryinfo

Created: 12/06/2025 05:04
Updated: 12/09/2025 22:27
Changes: 12/06/2025 05:04 (67), 12/08/2025 16:46 (7), 12/09/2025 22:27 (11)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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