xwiki-platform: Improper Encoding or Escaping of Output
CVE-2023-45135 is a high-severity improper encoding or escaping of output vulnerability in xwiki-platform from XWiki, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. The record lists versions 14.10.12, 15.5-rc-1 as the first without the flaw, so updating xwiki-platform to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.91% chance of exploitation within 30 days, higher than 80% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update xwiki-platform to 14.10.12 or 15.5-rc-1, whichever matches your release line, or a later version.
- Update Xwiki to 14.10.12 or 15.5, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| XWiki | xwiki-platform | >= 7.2-milestone-2, < 14.10.12; >= 15.0-rc-1, < 15.5-rc-1; 7.2-milestone-2 up to, but not including, 14.10.12; 15.0-rc-1 up to, but not including, 15.5-rc-1 | 14.10.12, 15.5-rc-1 |
| XWiki | Xwiki | 7.3 up to, but not including, 14.10.12; 15.0 up to, but not including, 15.5; 7.2 | 14.10.12, 15.5 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.0 | Critical | CNA (github.com) |
| CVSS 3.1 | 8.0 | High | NVD |
Official description
XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. In `org.xwiki.platform:xwiki-platform-web` versions 7.2-milestone-2 until 14.10.12 and `org.xwiki.platform:xwiki-platform-web-templates` prior to versions 14.10.12 and 15.5-rc-1, it is possible to pass a title to the page creation action that isn't displayed at first but then executed in the second step. This can be used by an attacker to trick a victim to execute code, allowing script execution if the victim has script right or remote code execution including full access to the XWiki instance if the victim has programming right. For the attack to work, the attacker needs to convince the victim to visit a link like `<xwiki-host>/xwiki/bin/create/NonExistingSpace/WebHome?title=$services.logging.getLogger(%22foo%22).error(%22Script%20executed!%22)` where `<xwiki-host>` is the URL of the Wiki installation and to then click on the "Create" button on that page. The page looks like a regular XWiki page that the victim would also see when clicking the button to create a page that doesn't exist yet, the malicious code is not displayed anywhere on that page. After clicking the "Create" button, the malicious title would be displayed but at this point, the code has already been executed and the attacker could use this code also to hide the attack, e.g., by redirecting the victim again to the same page with an innocent title. It thus seems plausible that this attack could work if the attacker can place a fake "create page" button on a page which is possible with edit right. This has been patched in `org.xwiki.platform:xwiki-platform-web` version 14.10.12 and `org.xwiki.platform:xwiki-platform-web-templates` versions 14.10.12 and 15.5-rc-1 by displaying the title already in the first step such that the victim can notice the attack before continuing. It is possible to manually patch the modified files from the patch in an existing installation. For the JavaScript change, the minified JavaScript file would need to be obtained from a build of XWiki and replaced accordingly.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Encoding or Escaping of Output
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
How developers prevent this class of flaw
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
- If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
More Improper Encoding or Escaping of Output vulnerabilities (CWE-116)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/xwiki/xwiki-platform/security/advisories/GHSA-ghf6-2f42-mjh9Exploit
- jira.xwiki.org/browse/XWIKI-20869Exploit, Issue Tracking
Patches and release notes
Other vulnerabilities in xwiki-platform
- 7.1 High severity
- 8.2 High severity
- 7.5 High severity
- 9.3 Critical severity
- 8.6 High severity
- 7.5 High severity
Recent Improper Encoding or Escaping of Output vulnerabilities
- 7.8 High severity
- 8.6 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.2 High severity
- 8.8 High severity
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