CVE-2026-40104: XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it

This month

HIGH 8.2REMOTEUPGRADE

CVE-2026-40104 is a high-severity flaw (CVSS 8.2) affecting xwiki. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Versions 1.8-rc-1, 17.0.0-rc-1 and 17.5.0-rc-1 and prior include a resource exhaustion vulnerability in REST API endpoints such as /xwiki/rest/wikis/xwiki/spaces/AnnotationCode/pages/AnnotationConfig/objects/AnnotationCode.AnnotationConfig/0/properties, which list all available pages as part of the metadata for database list properties without

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 66%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-04-15
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: xwiki

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-15 04:17 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

xwiki xwiki UPGRADE

Affected: >= 1.8 and < 16.10.16 · >= 17.0.0 and < 17.4.8 · >= 17.5.0 and < 17.10.1

Fixed in: 16.10.16, 17.4.8, 17.10.1

Safe to downgrade to: a release before 1.8

1. Check installed version

apt-cache policy xwiki || rpm -q xwiki || xwiki --version

2. UPGRADE to 16.10.16 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade xwiki

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade xwiki

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.8 (Debian / Ubuntu)

apt-cache madison xwiki sudo apt install xwiki=<VERSION_BEFORE_1.8> sudo apt-mark hold xwiki

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list xwiki sudo dnf downgrade xwiki-<VERSION_BEFORE_1.8> sudo dnf versionlock add xwiki

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40104?

xwiki: upgrade to 16.10.16, 17.4.8, 17.10.1. Exact commands for each OS are on this page.

Is CVE-2026-40104 being exploited?

CVE-2026-40104 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40104 affect?

CVE-2026-40104 affects xwiki. Severity is high (CVSS 8.2). XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Versions 1.8-rc-1, 17.0.0-rc-1 and 17.5.0-rc-1 and prior include a resource exhaustion vulnerability in REST API endpoints such as /xwi

How urgent is CVE-2026-40104?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-40105 MEDIUM 6.1 UPGRADE XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it
CVE-2023-29525 CRITICAL 9.9 UPGRADE XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it

References

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