CVE-2026-55779 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in silverstripe/versioned. A fix is available for silverstripe/versioned — see the affected versions and patch details below.
Silverstripe Versioned: XSS in archive admin restore
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55779.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-55779 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
silverstripe/versionedReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Silverstripe Versioned provides versioning for Silverstripe models. Prior to 3.2.1, RestoreAction::getRestoreMessage() in src/RestoreAction.php builds ArchiveAdmin restore notifications rendered as CAST_HTML and inserts $restoredItem->Title, $restoredItem->URLSegment, $restoredItem->CMSEditLink(), and $changedProperty['value'] without applying Convert::raw2xml(). When an administrator restores an archived page containing a crafted title or URL segment, the generated restoration message can execute stored JavaScript in the administrator's browser, compromising the confidentiality and integrity of the CMS session. This issue is fixed in version 3.2.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | silverstripe/versioned | all versions | 3.2.1composer require silverstripe/versioned:^3.2.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for silverstripe/versioned, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update silverstripe/versioned to 3.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55779 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
Is CVE-2026-55779 in your dependencies?
Find it across Packagist, including transitive dependencies.