PT-2026-42581 · Unknown · Concrete Cms

Tenzai + 1 · Published 2026-05-21 · Updated 2026-05-26 · CVE-2026-8139

Positive Technologies (AI Summary)

CVSS v3.1

5.4

Medium

Base vector

AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions Concrete CMS versions prior to 9.5.1

Description Stored Cross-Site Scripting (XSS) occurs via the 'external-link' page cvName because the updateCollectionAliasExternal() function bypasses sanitization. Stored XSS is a flaw where malicious scripts are permanently stored on the target server, which then serves them to other users.

Recommendations Update to a version newer than 9.5.0. As a temporary workaround, restrict access to the updateCollectionAliasExternal() function to minimize the risk of exploitation.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-8139

Affected Products

Concrete Cms

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-8139 · Security Note
• https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes · Vendor Advisory
• https://twitter.com/CVEnew/status/2057783192954806555 · Twitter Post
• https://t.me/cveNotify/164723 · Telegram Post