CVE-2021-44542Network attack vector

Service interruption via unreleased request buffers

Published Dec 23, 2021 · Updated Aug 4, 2024

Memory leak in send_http_request() in Privoxy before 3.0.33 allows remote attackers to exhaust memory through forwarding errors. Error-return paths in the function omit cleanup of allocated request data, so repeated failed forwarding operations accumulate memory. No authentication or user interaction is required; sustained requests that force forwarding errors can exhaust process memory and interrupt the proxy service.

CVSS severity7.5
High
EPSS probability1.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in send_http_request() in Privoxy before 3.0.33 allows remote attackers to exhaust memory through forwarding errors. Error-return paths in the function omit cleanup of allocated request data, so repeated failed forwarding operations accumulate memory. No authentication or user interaction is required; sustained requests that force forwarding errors can exhaust process memory and interrupt the proxy service.

The record

CVE
CVE-2021-44542
Published
Dec 23, 2021
Updated
Aug 4, 2024
Vendor
Privoxy Developers
Product
Privoxy
Classifications
CWE-401, T1499.003
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

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-401Missing Release of Memory after Effective Lifetime
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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