CVE-2020-26693Network attack vector

Stored XSS via unescaped load balancer fields

Published Jun 1, 2021 · Updated Aug 4, 2024

Stored XSS in pfSense 2.4.5-p1 allows remote authenticated users to execute arbitrary web scripts through load balancer monitors. load_balancer_monitor.php renders stored monitor name, type, and description values without HTML encoding, while the editor accepts an unlisted type. An authenticated user must store a crafted monitor value and another user must view the monitor list, enabling script execution in the viewer's browser.

CVSS severity5.4
Medium
EPSS probability5.31%
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 pfSense 2.4.5-p1 allows remote authenticated users to execute arbitrary web scripts through load balancer monitors. load_balancer_monitor.php renders stored monitor name, type, and description values without HTML encoding, while the editor accepts an unlisted type. An authenticated user must store a crafted monitor value and another user must view the monitor list, enabling script execution in the viewer's browser.

The record

CVE
CVE-2020-26693
Published
Jun 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 1, 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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')
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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