CVE-2025-53835: XWiki Rendering is vulnerable to XSS attacks through insecure XHTML syntax

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.4%, percentile 34: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 34% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes org.xwiki.rendering:xwiki-rendering-syntax-xhtml (Maven) >= 5.4.5, < 14.10, fixed in 14.10. Check your lockfile, including transitive dependencies.

What it is

XWiki Rendering is a generic rendering system that converts textual input in a given syntax (wiki syntax, HTML, etc) into another syntax (XHTML, etc). Starting in version 5.4.5 and prior to version 14.10, the XHTML syntax depended on the xdom+xml/current syntax which allows the creation of raw blocks that permit the insertion of arbitrary HTML content including JavaScript. This allows XSS attacks for users who can edit a document like their user profile (enabled by default). This has been fixed in version 14.10 by removing the dependency on the xdom+xml/current syntax from the XHTML syntax. Note that the xdom+xml syntax is still vulnerable to this attack. As it's main purpose is testing and its use is quite difficult, this syntax shouldn't be installed or used on a regular wiki. There are no known workarounds apart from upgrading.

From the GitHub advisory

Impact The XHTML syntax depended on the xdom+xml/current syntax which allows the creation of raw blocks that permit the insertion of arbitrary HTML content including JavaScript. This allows XSS attacks for users who can edit a document like their user profile (enabled by default). The attack works by setting the document's syntax to xdom+xml/current and then inserting content like

This has been fixed by removing the dependency on the xdom+xml/current syntax from the XHTML syntax. Note that the xdom+xml syntax is still vulnerable to this attack. As it's main purpose is testing and its use is quite difficult, this syntax shouldn't be installed or used on a regular wiki. We're currently not aware of any further dependencies on it.

Patches The fix of removing the dependency has been included in XWiki 14.10. It is not released for earlier versions due to the potential breakages, among others this change makes it necessary to update the Confluence XHTML syntax as it relies on internals that were changed for the fix. Similar XSS fixes were also not applied to the LTS version 13.10.x due to the potential breakages.

Workarounds There are no known workarounds apart from upgrading.

References https://jira.xwiki.org/browse/XRENDERING-660 https://github.com/xwiki/xwiki-rendering/commit/a4ca31f99f524b9456c64150d6f375984aa81ea7

Weakness type: CWE-79, CWE-80.

Product: org.xwiki.rendering:xwiki-rendering-syntax-xhtml (Maven) · Assigned by: GitHub_M · Published: 2025-07-14

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.41% probability of exploitation activity in the next 30 days; percentile 34.

Timeline

• 2025-07-14 — CVE record published by GitHub_M
• 2025-07-14 — GitHub-reviewed advisory GHSA-w3wh-g4m9-783p published (critical)
• 2025-07-15 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-w3wh-g4m9-783p github.com
2. CVE.org record CVE-2025-53835 cve.org
3. NVD entry CVE-2025-53835 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. jira.xwiki.org jira.xwiki.org

Critical Maven advisories · Today’s Security Digest