CVE-2026-81925Network attack vectorHinoki check available

Reflected XSS via unsanitized custom date format

Published Sep 15, 2026 · Updated Sep 15, 2026

Reflected XSS in Concrete CMS before 9.5.3 allows remote attackers to execute JavaScript in a user's browser via a crafted POST request. Conversation message rendering fails to neutralize a user-supplied custom date format before inserting it into the response. Exploitation requires a user to submit the cross-origin POST, while the endpoint's missing CSRF token enables delivery without prior authentication.

CVSS severity2.1
Low
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Reflected XSS in Concrete CMS before 9.5.3 allows remote attackers to execute JavaScript in a user's browser via a crafted POST request. Conversation message rendering fails to neutralize a user-supplied custom date format before inserting it into the response. Exploitation requires a user to submit the cross-origin POST, while the endpoint's missing CSRF token enables delivery without prior authentication.

The record

CVE
CVE-2026-81925
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
Concrete CMS
Product
Concrete CMS
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.0.0 <=9.5.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Concrete CMS · Concrete CMSversion=5.0.0 <=9.5.2

Published CVSS scores

2.1Concrete CMS security teamCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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