CVE-2021-44543Network attack vector

Cross-site scripting via unencoded template name

Published Dec 23, 2021 · Updated Aug 4, 2024

Cross-site scripting in Privoxy before 3.0.33 allows remote attackers to execute script in a user's browser via a crafted manual request. The cgi_error_no_template() error path inserts an attacker-controlled template name into an HTML response without encoding it. Exploitation requires Privoxy to serve its local user manual and a user to render the crafted response; the resulting script runs in the page's browser context.

CVSS severity6.1
Medium
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Privoxy before 3.0.33 allows remote attackers to execute script in a user's browser via a crafted manual request. The cgi_error_no_template() error path inserts an attacker-controlled template name into an HTML response without encoding it. Exploitation requires Privoxy to serve its local user manual and a user to render the crafted response; the resulting script runs in the page's browser context.

The record

CVE
CVE-2021-44543
Published
Dec 23, 2021
Updated
Aug 4, 2024
Vendor
Privoxy Developers
Product
Privoxy
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 23, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Privoxy 3.0.33

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Privoxy Developers · Privoxyversion=Privoxy 3.0.33

Published CVSS scores

2.6NIST NVDAV:N/AC:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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')
T1189Drive-by Compromise

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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