Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via OAuth integration name

published 2026-05-21 5 mo ago modified 2026-09-10 1 mo ago also GHSA-h72c-xx3w-w8h7 , EUVD-2026-31342

cvss: 4.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via OAuth integration name. The OAuth authorize template renders the integration name (admin-controlled) through Concrete's t() translation helper as a sprintf-style format. The <strong>...</strong> wrap is built by PHP string interpolation before t() runs, so the integration name lands in the translated output as raw HTML. A rogue admin could potentially snoop on login submissions.The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Thanks Yonatan Drori (Tenzai) for reporting.

Patch / fix

fixed in 1

packagist concrete5/concrete5 9.5.1

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 5 mo ago (2026-05-22)

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	7.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA	4.0	7.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	4.8	CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	concrete5/concrete5	<9.5.1	9.5.1

Affected products

Concrete CMS Concrete CMS

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

documentation.concretecms.org /9-x/developers/introduction/version-history/951-release-notes
release-notes, web
nvd.nist.gov /vuln/detail/CVE-2026-8197
advisory
github.com /concretecms/concretecms
package

Sources

CVE List CVE-2026-8197
GitHub Advisory GHSA-h72c-xx3w-w8h7
NVD CVE-2026-8197

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Summary