How severe is GHSA-663w-2xp3-5739?

GHSA-663w-2xp3-5739 has a CVSS score of 9.6/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-663w-2xp3-5739?

GHSA-663w-2xp3-5739 affects the following packages: org.xwiki.rendering:xwiki-rendering-xml (Maven). Ecosystems affected: Maven.

How do I fix GHSA-663w-2xp3-5739?

Update org.xwiki.rendering:xwiki-rendering-xml to 14.10.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-663w-2xp3-5739 is resolved across your whole dependency graph.

How do I detect GHSA-663w-2xp3-5739 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.xwiki.rendering:xwiki-rendering-xml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-663w-2xp3-5739 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is GHSA-663w-2xp3-5739 actively exploited in the wild?

Yes. There are 3 known exploit references for GHSA-663w-2xp3-5739, including 3 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-663w-2xp3-5739?

GHSA-663w-2xp3-5739 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 66th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-663w-2xp3-5739?

GHSA-663w-2xp3-5739 is classified as CWE-83 (CWE-83), Cross-site Scripting (XSS) (CWE-79). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-663w-2xp3-5739 published, and has it been updated?

GHSA-663w-2xp3-5739 was published on October 25, 2023 and was last updated on February 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

org.xwiki.rendering:xwiki-rendering-xml Improper Neutralization of Invalid Characters in Identifiers in Web Pages vulnerabilityGHSA-663w-2xp3-5739

CRITICALFix: xwiki/xwiki-rendering@f4d5aca

GHSA-663w-2xp3-5739 is a critical-severity (CVSS 9.6) CWE-83 vulnerability in org.xwiki.rendering:xwiki-rendering-xml. 3 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for org.xwiki.rendering:xwiki-rendering-xml — see the affected versions and patch details below.

Also known asCVE-2023-37908

Published

Oct 25, 2023

Updated

Feb 4, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

3 known

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for GHSA-663w-2xp3-5739.

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk+0.05%

Lower risk than most CVEs66th percentile — riskier than 66% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.xwiki.rendering:xwiki-rendering-xml

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

The cleaning of attributes during XHTML rendering, introduced in version 14.6-rc-1, allowed the injection of arbitrary HTML code and thus cross-site scripting via invalid attribute names. This can be exploited, e.g., via the link syntax in any content that supports XWiki syntax like comments in XWiki:

[[Link1>>https://XWiki.example.com||/onmouseover="alert('XSS1')"]]

When a user moves the mouse over this link, the malicious JavaScript code is executed in the context of the user session. When this user is a privileged user who has programming rights, this allows server-side code execution with programming rights, impacting the confidentiality, integrity and availability of the XWiki instance.

While this attribute was correctly recognized as not allowed, the attribute was still printed with a prefix data-xwiki-translated-attribute- without further cleaning or validation.

Note that while versions below 14.6 are not vulnerable to this particular vulnerability, they are still vulnerable to XSS through attributes in XWiki syntax, see the corresponding advisory.

Patches

This problem has been patched in XWiki 14.10.4 and 15.0 RC1 by removing characters not allowed in data attributes and then validating the cleaned attribute again.

Workarounds

There are no known workarounds apart from upgrading to a version including the fix.

References

For more information

If you have any questions or comments about this advisory:

Open an issue in Jira XWiki
Email us at XWiki Security mailing-list

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.xwiki.rendering:xwiki-rendering-xml`	≥ 14.6-rc-1&&< 14.10.4	14.10.4`org.xwiki.rendering:xwiki-rendering-xml:14.10.4`

Affected Products

1 product · 1 configurations

Application

xwiki-renderingxwiki

≥ 14.6 && < 14.10.4

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

XWiki Rendering is a generic Rendering system that converts textual inpu…

github.comNVDOct 2023

Report on jira.xwiki.org

jira.xwiki.orgNVDOct 2023

Report on github.com

github.comNVDOct 2023

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.xwiki.rendering:xwiki-rendering-xml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.xwiki.rendering:xwiki-rendering-xml to 14.10.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-663w-2xp3-5739 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Impact The cleaning of attributes during XHTML rendering, introduced in version 14.6-rc-1, allowed the injection of arbitrary HTML code and thus cross-site scripting via invalid attribute names. This can be exploited, e.g., via the link syntax in any content that supports XWiki syntax like comments in XWiki: ``` [[Link1>>https://XWiki.example.com||/onmouseover="alert('XSS1')"]] ``` When a user moves the mouse over this link, the malicious JavaScript code is executed in the context of the user session. When this user is a privileged user who has programming rights, this allows server-sid