CVE-2023-28820Network attack vector

Stored script execution via unsanitized RSS link

Published Apr 28, 2023 · Updated Jan 31, 2025

Stored XSS in Concrete CMS RSS Displayer before 9.1 allows remote authenticated users to execute stored script in visitors' browsers through a crafted feed link. The RSS Displayer outputs the link element href from feed input without sanitizing the attacker-controlled value. Administrator access and a victim viewing the affected RSS output are required; execution can expose data accessible to the victim's browser.

CVSS severity2.0
Low
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Concrete CMS RSS Displayer before 9.1 allows remote authenticated users to execute stored script in visitors' browsers through a crafted feed link. The RSS Displayer outputs the link element href from feed input without sanitizing the attacker-controlled value. Administrator access and a victim viewing the affected RSS output are required; execution can expose data accessible to the victim's browser.

The record

CVE
CVE-2023-28820
Published
Apr 28, 2023
Updated
Jan 31, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Apr 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 31, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

2.0Concrete CMS Security TeamCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:N/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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