CVE-2026-33137: XWiki Platform has an Unauthenticated XAR Import via REST /wikis/{wikiName}

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.9%, percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.xwiki.platform:xwiki-platform-rest-server (Maven) >= 15.10.6, < 16.10.17, fixed in 16.10.17; org.xwiki.platform:xwiki-platform-rest-server (Maven) >= 17.0.0-rc-1, < 17.4.9, fixed in 17.4.9; org.xwiki.platform:xwiki-platform-rest-server (Maven) >= 17.5.0, < 17.10.3, fixed in 17.10.3; org.xwiki.platform:xwiki-platform-rest-server (Maven) >= 18.0.0-rc-1, < 18.1.0-rc-1, fixed in 18.1.0-rc-1. Check your lockfile, including transitive dependencies.

What it is

XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. XWiki Platform is a generic wiki platform. In versions starting with 15.10.6 and prior to 18.1.0-rc-1, 17.10.3, 17.4.9, and 16.10.17, the POST /wikis/{wikiName} API executes a XAR import without performing any authentication or authorization checks, allowing an unauthenticated attacker to create or update documents in the target wiki. This vulnerability has been patched in XWiki 16.10.17, 17.4.9, 17.10.3, 18.0.1 and 18.1.0-rc-1.

From the GitHub advisory

Impact

POST /wikis/{wikiName} executes a XAR import without performing any authentication or authorization checks, allowing an unauthenticated attacker to create or update documents in the target wiki

Patches

This vulnerability has been patched in XWiki 16.10.17, 17.4.9, 17.10.3, 18.0.1 and 18.1.0-rc-1.

Workarounds

Weakness type: CWE-862.

Product: org.xwiki.platform:xwiki-platform-rest-server (Maven) · Assigned by: GitHub_M · Published: 2026-05-20

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

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 none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.88% probability of exploitation activity in the next 30 days; percentile 59.

Timeline

• 2026-05-20 — CVE record published by GitHub_M
• 2026-05-26 — CVE record last updated
• 2026-05-26 — GitHub-reviewed advisory GHSA-qrvh-r3f2-9h4r published (critical)

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-qrvh-r3f2-9h4r github.com
2. CVE.org record CVE-2026-33137 cve.org
3. NVD entry CVE-2026-33137 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