Summaryinfo

A vulnerability classified as critical was found in Seafile Server up to 13.0.17-pro. Affected by this vulnerability is an unknown functionality of the component WebSocket Message Handler. Such manipulation leads to improper authentication. This vulnerability is documented as CVE-2026-30587. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Seafile Server up to 13.0.17-pro. It has been rated as critical. Affected by this issue is an unknown function of the component WebSocket Message Handler. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Multiple Stored XSS vulnerabilities exist in Seafile Server version 13.0.15,13.0.16-pro,12.0.14 and prior and fixed in 13.0.17, 13.0.17-pro, and 12.0.20-pro, via the Seadoc (sdoc) editor. The application fails to properly sanitize WebSocket messages regarding document structure updates. This allows authenticated remote attackers to inject malicious JavaScript payloads via the src attribute of embedded Excalidraw whiteboards or the href attribute of anchor tags

The advisory is shared for download at gist.github.com. This vulnerability is handled as CVE-2026-30587 since 03/04/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-15940). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Seafile

Name

• Server

Version

• 12.0.0
• 12.0.1
• 12.0.2
• 12.0.3
• 12.0.4
• 12.0.5
• 12.0.6
• 12.0.7
• 12.0.8
• 12.0.9
• 12.0.10
• 12.0.11
• 12.0.12
• 12.0.13
• 12.0.14
• 12.0.20-pro
• 13.0.0
• 13.0.1
• 13.0.2
• 13.0.3
• 13.0.4
• 13.0.5
• 13.0.6
• 13.0.7
• 13.0.8
• 13.0.9
• 13.0.10
• 13.0.11
• 13.0.12
• 13.0.13
• 13.0.14
• 13.0.15
• 13.0.16
• 13.0.16-pro
• 13.0.17
• 13.0.17-pro

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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