CVE-2026-7890: Concrete CMS's RSS Displayer block accepts a feed URL from any page editor and fetches it server-side without validation

May 22, 2026 (updated June 24, 2026)

In Concrete CMS 9.5.0 and below, the RSS Displayer block accepts a feed URL from any page editor and fetches it server-side without validation enabling redirect-to-internal bypasses.

References

documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
github.com/advisories/GHSA-gjwq-9v8p-47w7
nvd.nist.gov/vuln/detail/CVE-2026-7890

Code Behaviors & Features

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