Concrete CMS before 9.5.3 improperly neutralized a user-supplied custom date format when rendering conversation messages, resulting in reflected cross-site scripting. An attacker could execute arbitrary JavaScript in the browser of a user who was tricked into submitting a crafted POST request to the conversation view endpoint. Exploitation was aided by the absence of a CSRF token on the endpoint, which allowed the payload to be delivered through an auto-submitting cross-origin POST without authentication. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.
{
"cna_assigner": "ConcreteCMS",
"cwe_ids": [
"CWE-79"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81925.json"
}{
"cpe": "cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "5.0.0"
},
{
"last_affected": "9.5.2"
},
{
"introduced": "0"
},
{
"fixed": "9.5.3"
}
],
"source": [
"AFFECTED_FIELD",
"CPE_RANGE"
]
}