CVE-2021-33425Public exploitNetwork attack vector

Stored XSS via unsanitized UCI hostname rendering

Published May 25, 2021 · Updated Jul 9, 2026

Stored XSS in OpenWrt LuCI 19.07.0 through 19.07.7 allows remote authenticated users to execute JavaScript via a crafted hostname. Affected LuCI theme templates render the UCI hostname without stripping malicious script markup, so stored input becomes executable page content. The attacker must be permitted to change the UCI hostname, normally as root, and a user must view an affected template; the script then runs in that viewer’s browser origin.

CVSS severity5.4
Medium
EPSS probability0.51%
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 OpenWrt LuCI 19.07.0 through 19.07.7 allows remote authenticated users to execute JavaScript via a crafted hostname. Affected LuCI theme templates render the UCI hostname without stripping malicious script markup, so stored input becomes executable page content. The attacker must be permitted to change the UCI hostname, normally as root, and a user must view an affected template; the script then runs in that viewer’s browser origin.

The record

CVE
CVE-2021-33425
Published
May 25, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 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?

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

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 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')
T1059.007Command and Scripting Interpreter: JavaScript

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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