Multiple vulnerabilities in Collabora Online

12/03/2024 - Download


Collabora Online



Fixed Version(s)

coolwsd ≥ 23.05.9, 22.05.22,

Affected Version(s)

coolwsd < 23.05.9, 22.05.22,

CVE Number



Damien Couturier



Collabora Online is a server service built from the main LibreOffice project code providing display and collaborative visual editing of a range of document types in a web browser. It is used by applications such as Zimbra (Zimbra Docs Zimlet) or ownCloud.


Synacktiv discovered the following vulnerabilities affecting Collabora Online:

  • SSRF (Sever Side Request Forgery) using webservice().
  • SSRF (Server Side Request Forgery) / file disclosure using file converter.
  • Sensitive information disclosure to users (JailID).

The severity of the 2 SSRF vulnerabilities greatly depends on the environment, but should be considered from medium to high. These vulnerabilities were independently reported to Collabora Online security team by ubercomp with CVE-2023-49788.

The JailID disclosure is a low-severity vulnerability and was attributed CVE-2024-25114.



Date Description
2024.01.18 Advisory sent to
2024.01.19 Acknowledgment from Collabora Online that the 2 SSRFs are already known and patched with CVE-2023-49788.
2024.02.12 CVE-2024-25114 assigned to the JailID disclosure vulnerability.
2024.03.12 Public release.


Technical details

SSRF (Sever Side Request Forgery) using webservice()


Using Collabora Online (cool) it is possible to create/edit LibreOffice Calc documents, using the usual LibreOffice functions available for users. With the webservice() function it is possible to request an arbitrary URL using http or https URL scheme. For instance, one can request either an external resource or an internal one (cool web service is listening on port 9980):

Requesting lool webservice listenning on port 9980


In a cloud environment it is thus possible to request the metadata endpoint, such as for OpenStack:

reading OpenStack configuration files

For instance CollaboraOnline is deployed in an AWS environment:

Disclosing CollaboraOnline secrets linked to AWS.


The impact of of this vulnerability depends on the environment in which the lool service is running. It could be possible to access internal services, but also metadata endpoints in a cloud environment.


SSRF (Server Side Request Forgery) / file disclosure using file converter


LibreOffice documents can embed OLE objects. When the document is converted to Excel 2003, the path to the OLE object will be processed accordingly:

  • To a file if using the file scheme.
  • To a server resource if using the http, https or ftp schemes.

By proceeding to the following steps, a user could access local files on the server:

  • Create a local LibreOffice document.
  • Insert an OLE object pointing to a benign file (e.g. /etc/hosts).
  • Save the file.
  • Change the path to /etc/passwd by editing the content.xml file in the document.
  • Upload it to LibreOffice Online.
  • Download it as an Excel 2003 Spreadsheet.
Updating content of the OLE object.


Once opened locally in LibreOffice, the content of the /etc/passwd file from the remote server is revealed:

Reading passwd file from lool worker


The same process can be used with an http/https scheme to request a local or remote service and get the answer.


The Collabora Online worker being heavily sandboxed (mount jail, seccomp, etc.) by default, the impact of the file disclosure is limited. However, using http/https schemes, the same issues raised in the previous vulnerability have to be taken into account (access to cloud metadata endpoints).

CVE-2024-25114 - Sensitive information disclosure to users (JailID).


Collabora Online uses random IDs on top of sandboxing to limit the impact of vulnerabilities in the cool worker.

"Note: for security reasons, this directory name is randomly generated and should not be given out to the client. Since there is only one ForKit per WSD instance, there is also one JailID between them."1

Using the native CELL() function from LibreOffice, a user can access this JailID with the help of CELL("filename"):

Jailid disclosure to user



The impact of this vulnerability in its own is low because it requires to be chained with another vulnerability.