OpenSlides up to 4.2.28 access control

Summaryinfo

A vulnerability classified as critical was found in OpenSlides up to 4.2.28. This affects an unknown part. Such manipulation leads to access control. This vulnerability is documented as CVE-2026-25519. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in OpenSlides up to 4.2.28. It has been rated as critical. Affected by this issue is an unknown function. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

OpenSlides is a free, web based presentation and assembly system for managing and projecting agenda, motions and elections of an assembly. Prior to version 4.2.29, OpenSlides supports local logins with username and password or an optionally configurable single sign on with SAML via an external IDP. For users synced to OpenSlides via an external IDP, there is an incorrect access control regarding the local login of these users. Users can successfully login using the local login form and the OpenSlides username of a SAML user and a trivial password. This password is valid for all SAML users. This issue has been patched in version 4.2.29.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-25519 since 02/02/2026. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1068.

Upgrading to version 4.2.29 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 70c1aa9f5e1db59ec120ecce98d1c1169350a4ee 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 EUVD (EUVD-2026-5342). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• OpenSlides

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7
• 4.2.8
• 4.2.9
• 4.2.10
• 4.2.11
• 4.2.12
• 4.2.13
• 4.2.14
• 4.2.15
• 4.2.16
• 4.2.17
• 4.2.18
• 4.2.19
• 4.2.20
• 4.2.21
• 4.2.22
• 4.2.23
• 4.2.24
• 4.2.25
• 4.2.26
• 4.2.27
• 4.2.28

License

• open-source

Website

• Product: https://github.com/OpenSlides/OpenSlides/

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Entryinfo

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

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