CVE-2026-81927 (GCVE-0-2026-81927)

Vulnerability from cvelistv5 – Published: 2026-09-15 20:21 – Updated: 2026-09-16 17:52
VLAI
Title
Concrete CMS before 9.5.3 is vulnerable to Stored XSS via SVG upload in "Reject" sanitization mode
Summary
Concrete CMS before 9.5.3 contained a stored cross-site scripting vulnerability in SVG file handling. When SVG processing was set to the non-default "Reject files containing potentially harmful elements" mode (concrete.file_manager.images.svg_sanitization.action = reject), uploaded SVGs were checked only against a small built-in blocklist covering the script element and on* event-handler attributes; the broader enshrined/svg-sanitize pass still ran, but its result was discarded, so vectors it would have stripped, such as a javascript: URI in an xlink:href, were stored unmodified and executed when the file was opened directly. A user able to upload files could thereby run arbitrary JavaScript in the browser of any user who viewed the file. The default sanitize mode was not affected. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 1.8 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Oriol Ortiz for reporting.
Severity
1.8 (Low)
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-16 17:52 UTC
CWE
  • CWE-79 - Improper neutralization of input during web page generation ('cross-site scripting')
Assigner
ConcreteCMS CNA under the mitre root
CNA scorecard B 84/100 over 111 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Concrete CMS Concrete CMS Affected: 5.0.0 , ≤ 9.5.2 (git)
guessed Create a notification for this product.
Credits
orisec
Show details on NVD website
To clipboard 

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