Concrete CMS is vulnerable to Stored XSS via external-link page cvName

MEDIUM 5.4CVE-2026-8139 · GHSA-pcrh-gj77-j4mw · Published 21/05/2026 · updated 23/07/2026

In short

CVE-2026-8139 is a MEDIUM (CVSS 5.4) vulnerability affecting concrete5/concrete5, concrete cms (concretecms).
Chance of exploitation in the next 30 days (EPSS): 0.15%, higher than 4.2% of all vulnerabilities.
Fix: update to 9.5.1 or later.

Package	Affected versions	Patched versions
concrete5/concrete5 Packagist	`< 9.5.1`	`9.5.1`
concrete cms concretecms	`≤ 9.5.0`	No fix yet

Description

Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized.

NVD description

Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

References

nvd.nist.gov/vuln/detail/CVE-2026-8139 · ADVISORY
documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes · WEB
concretecms/concretecms · PACKAGE

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Package

Affected versions

Patched versions

concrete5/concrete5

Packagist

< 9.5.1

9.5.1

concrete cms

concretecms

≤ 9.5.0

No fix yet

Description

Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized.

NVD description

More vulnerabilities in concrete5/concrete5

See all →