The goal of this document is to provide some information about the policy of XWiki.org in case a vulnerability is found in XWiki Standard.

What are the available channels to discuss about security issues?

Four channels are available with different usages.

These channels are private because we want to apply the following strategy:

• Don't make it too easy for hackers to find about security issues before we've had the chance to provide a fix that our users can apply on their XWiki instances.
• Once we have fixed a security issue and released XWiki versions with the fix, and after a defined waiting period (see below for more details) to allow users to upgrade, the seecurity issue is disclosed publicly.

Security Forum & Mailing-List

The main discussion channel is the private security forum category . However, this channel is private and for this reason, we've kept the old mailing-list (security[at]xwiki.org) since anyone can post on it (but only core committers and some other trusted persons can read them). See also Mailing Lists.

The forum channel must be used for warning the sponsoring companies that a new security issue has been discovered. It might be used for asking about a potential security issue.

JIRA

The JIRA of XWiki (https://jira.xwiki.org) is the right place to submit issues by using the level set to Confidential and the security label. Those issues are only visible to people who submitted them, to the committers of XWiki, and to anyone trusted by the XWiki committers who can help fixing them. All informations about the submitted issues if discussed elsewhere should be added on the comments of the issues so that the reporter can follow them. Note that the label “security” could be used in JIRA dashboard or in Release Notes to inform about the fixed security issues.

Matrix

A private dedicated Matrix Chat room is dedicated to talk about security issues but is dedicated to the same people as the security mailing-list. It should be mainly used to discuss about the security policy and technical details about a specific issue.

More information is available on the Chat page.

Github Security Advisories

For each security issue fixed for XWiki, a dedicated security advisory is created on Github. Those advisories remain private until they are publicly disclosed. By default, the owners of a Github organization can view the advisories: in the case of XWiki, the Github organization is owned by all XWiki committers.

On top of that, access to the advisories is also manually granted to a dedicated Github Team for trusted people who are not committers, to see the advisories before they are publicly disclosed.

People wanting to get access to this Github Team should request access on the security mailing-list.

Where to submit security issues?

As specified above, all security issues should be submitted on https://jira.xwiki.org with the level set to Confidential and the security label. Try to give as much information as possible for those issues and in particular a way to exploit the vulnerability, or a way to assess that the vulnerability is present: we will use it to determine if some instances are subject to it or not.

Those issues are only visible to people who submitted them, to the committers of XWiki and to anyone trusted by the XWiki committers who could help fixing them.

What are the criteria for computing severity?

The severity is defined case by case by the core committers depending on two criteria:

• the impact of the security issue (e.g. an issue that might impact all pages of a wiki is more severe than an issue which might impact only pages with specific rights)
• and the difficulty to reproduce it (e.g. an issue which needs script rights to be reproduced is less severe than an issue which only needs view access on the wiki)

We currently use two types of labels to compute the severity of an issue: the type of attacker (depending on its rights on the wiki) and the type of attack (depending on what he can actually do).

Types of attackers

Types of attacks

Severity

The severity of the security tickets should be computed using a CVSS calculator such as https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator.

Note that we only use the base metrics right now for computing CVSS in XWiki.

A proposed severity mapping for our JIRA tickets using the CVSS score is the following:

• 0.1 - 3.9: Minor
• 4.0 - 6.9: Major
• 7.0 - 8.9: Critical
• 9.0 - 10.0: Blocker

Best practices for computing CVSS

In general it's good to refer to the official documentation for understanding CVSS, and to also look on the examples to better understand the different criteria.
Besides this, some best practices have been established for computing CVSS specifically for XWiki tickets.

Attack vector

It should always be Network.

Attack complexity

We don't have a specific best practice for this yet: the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Privileges Required

We defined the following mapping to apply the privileges required from CVSS which is a very discretized scope, to the continuum of rights from XWiki:

• None: Apply for any vulnerability that might be done with Guest user with standard XWiki right, AND with Guest user with Comment right as it’s a supported UC in XWiki which is supposed to prevent giving more rights to Guest
• Low: Apply for any vulnerability that might be done with registered users with standard XWiki right (note that it includes Script right for XWiki < 14.10)
• High: Apply for any vulnerability that involves more right than the standard XWiki right (can be allowing Script right for XWiki 14.10+, or Delete on the whole wiki, admin on a space etc)

Note that when we refer to standard XWiki right above we mean bundled rights scheme in Xwiki Standard.

User Interaction

We don't have a specific best practice for this yet: the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Scope

We don't have a specific best practice for this yet: the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Confidentiality Impact

In case of XSS vulnerability the impact should always be set to High.

For other cases the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Integrity Impact

In case of XSS vulnerability the impact should always be set to High.

For other cases the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Availability Impact

In case of XSS vulnerability the impact should always be set to High.

For other cases the official definition and examples should be used to define the value. In case of doubt, best is to discuss with the community.

Deprecated Severity Matrix

DISCLAIMER: This severity matrix is only indicative, the severity is computed on a case-by-case basis only.

How to read this matrix:

• columns are representing the type of attackers
• lines are representing the type of attacks
• values are a severity between high / medium / low

Note: in the future we’ll need to formalize the usage of https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator to compute the severity of our security.

How long does it take to fix a security issue?

The priority of the JIRA issue is set depending on the severity of the issue, we apply the following mapping:

• High severity: Blocker in JIRA
• Medium severity: Critical in JIRA
• Low severity: Major in JIRA

Blocker issues have to be fixed before the next release. There’s no obligations about critical and major issues, so they are handled depending on the other priorities of the core committers.

When is a security issue considered as fixed?

Security issues are considered as fixed only once the fix is part of releases for all supported branches impacted by the issue. So for example, if XWiki.org is currently in the 12.x cycle and a security issue impacts both 11.10.1 (LTS) and 12.3 (stable), the issue is fixed when 11.10.2 and 12.3.1 (or 12.4) are released with the fix.

Are security issues ever publicly disclosed?

Once the issue has been properly fixed and the fix has been released, a CVE is published to publicly disclose about this issue and to incitate for an upgrade. The CVE is mandatory for any security issues.

How long does it take to publish a CVE?

Once an issue has been fixed and released, an embargo of at least 3 months is starting to allow anyone working with XWiki to perform actions before the publication of the CVE. The embargo might be longer than 3 months, in which case extending the embargo might be decided through a vote on the forum. The sponsoring companies are automatically informed as soon as a security issues has been discovered through the security communication channels.

For example, if a security issue has been fixed and released in 11.10.2 and in 12.0, respectively released the 5th of February and the 29th of January, the CVE could be published 3 months after latest release: i.e. the 5th of May.

What’s the process to handle security issues for committers?

1. Take the ownership on the security issue by assigning the JIRA ticket to yourself.
2. Validate the information about the security issue
   • Verify that the Confidential level is set
   • Verify that the security labels are set and are correct
   • Verify that the security label is set (needed for example to know which issues are security issues when the Confidential level is removed)
   • Provide missing information, and, in particular, make sure that the issue contains reproduction steps to either exploit the vulnerability or assess its presence
3. Fix the issue on all supported branches
   • If you make a pull request (from a temporary private fork associated with the draft advisory) then don't merge it from the GitHub UI (i.e. from the advisory page) because the JIRA issue title will appear in the commit log, disclosing the security issue too soon. Use these steps instead.
4. Create a draft advisory on Github (see section below).
5. Add a link to the advisory draft on the JIRA issue(s)
6. Announce the fix on the security section of the forum with the list of branches where the fix is provided and the link to the advisory
7. When all XWiki versions where the fix is provided are released, announce on the security list that the 3 months embargo is starting and specify the date when the issue will be made public
8. After 3 months, request a CVE through GitHub Advisory page. Remove the Confidential level on the Jira issue. Publish the advisory once the CVE ID has been received.

Vulnerabilities in XWiki Dependencies

In addition to vulnerabilities directly related to the code of XWiki itself, some vulnerabilities can be introduced through the dependencies of XWiki and the extensions installed on it.

How to react if a vulnerability is found in a library or extension?

In most cases, it's possible to update the extension that contains a vulnerability. In a few cases, it's not possible to upgrade, but the vulnerable dependency has been analyzed and is not considered to directly affect the wiki: in such a case, the vulnerability is marked as analyzed, and the conclusions of the analysis are presented in the dashboard. Finally, if a vulnerability concerns a part that can't be updated because there is no new version and no analysis, you can contact us through the channels defined above.

For committers

When a new CVE is found in the CI, or raised by a user, follow those steps:

1. analyse the CVE
   2. see if an upgrade is possible and in this case release of new version of the impacted extensions
   3. add a review so that users of the dashboard are informed of our analysis, see the documentation for more details about the expected format

How long does it take to fix a vulnerable dependency?

First, a new version with a security fix must be available, and for that we depend on the third-party maintainers. Additionally, if it happens that an upgrade is not possible due to some technical limitations, we can implement a security fix within XWiki to make the issue non-exploitable (also note that many CVEs provide ways to mitigate the identified vulnerability), following our security fix policy.

Security Advisory template and information

For global information of creating a Github advisory, you can consult the official documentation: https://docs.github.com/en/code-security/security-advisories/repository-security-advisories/creating-a-repository-security-advisory.

You can find below a template to use for the content of a new security advisory:

The versions set in the security advisory should follow the best practices documented in https://docs.github.com/en/code-security/security-advisories/guidance-on-reporting-and-writing/best-practices-for-writing-repository-security-advisories#affected-versions. Then don't forget to pay attention to the format of the version (e.g. 14.10RC1 is not a right version: you should use 14.10-rc-1).

The severity of the vulnerability should be assessed using CVSS, you can find information and a calculator here to help you: https://www.first.org/cvss/v3-1/. You should also try to find a CWE corresponding to the vulnerability. You can browse and search for the closest one using the official website: https://cwe.mitre.org/data/index.html.

Finally you should not forget to add "XWiki/Security" Github Team as collaborator of your advisory to ensure proper people are able to see it.

Adding a new security member

Anyone can ask to get permissions to participate to XWiki Security topics by being added to the channels mentioned above (JIRA issues, Security chat, GitHub advisories, etc). The process is the following:

• You need to ask for permission by posting on the xwiki.org forum (in the Other category) and explain why you need access. 
• XWiki Committers will analyze your request and decide whether you will get access or not. The idea is to do a quick due diligence to check that the request is legit and that the person asking is known and is not going to use the private information for malicious purposes
• You'll then be asked on the forum to agree that you won't publicly disclose the non-public security information before the XWiki committers make it public, and that you agree to follow the rules defined in this security policy.
• You'll then get invited to all the private security channels.

Here's the checklist to add a new security member:

• Add the user to the JIRA security group (to be able to see existing security issues)
• Add the user to the Matrix #xwiki-security chat (to be able to discuss security issues)
• Add the user to the GitHub Security team (to be able to view non-published security advisories)
• Add the user to the XWikiSecurityGroup on xwiki.org (to be able to see the SecurityAdvisoryApplication)
• Add the user to the security group on the Forum.
• (optional) Add the user to the xwiki-security mailing list (to be able to see mails about security issues reported by the community)