CVE-2021-42650Network attack vector

User metadata disclosure via embedded image requests

Published Oct 18, 2021 · Updated Aug 4, 2024

Improper HTML neutralization in Portainer before 2.9.1 allows remote attackers to disclose viewer metadata via Custom Template notes. The note renderer accepts stored image elements and requests attacker-controlled image URLs instead of rejecting or encoding the markup. Exploitation requires a user or administrator to view the note; Portainer states that direct JavaScript injection is unavailable, limiting the demonstrated impact to IP address, browser, and location disclosure.

CVSS severity6.1
Medium
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper HTML neutralization in Portainer before 2.9.1 allows remote attackers to disclose viewer metadata via Custom Template notes. The note renderer accepts stored image elements and requests attacker-controlled image URLs instead of rejecting or encoding the markup. Exploitation requires a user or administrator to view the note; Portainer states that direct JavaScript injection is unavailable, limiting the demonstrated impact to IP address, browser, and location disclosure.

The record

CVE
CVE-2021-42650
Published
Oct 18, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

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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