CVE-2021-34815Public exploitNetwork attack vector

Credential phishing via unencoded login disclaimer

Published Jun 18, 2021 · Updated Aug 4, 2024

Stored XSS in CheckSec Canopy before 3.5.2 allows remote authenticated users to inject HTML into the login page. The LOGIN_PAGE_DISCLAIMER setting is embedded into the page without context-appropriate output encoding, so administrator-supplied markup executes when a user visits it. Administrator access is required to plant the payload, and user interaction can expose credentials through a phishing form without interrupting the service.

CVSS severity4.8
Medium
EPSS probability0.84%
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 CheckSec Canopy before 3.5.2 allows remote authenticated users to inject HTML into the login page. The LOGIN_PAGE_DISCLAIMER setting is embedded into the page without context-appropriate output encoding, so administrator-supplied markup executes when a user visits it. Administrator access is required to plant the payload, and user interaction can expose credentials through a phishing form without interrupting the service.

The record

CVE
CVE-2021-34815
Published
Jun 18, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1056.003
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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

4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1056.003Input Capture: Web Portal Capture

Public exploit references

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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