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Privoxy CVE-2016-1983

HIGH
Improper Input Validation (CWE-20)
2016-01-27 cve@mitre.org
7.5
CVSS 3.0 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V2 - Validation and Business Logic Input validation, allowlisting
Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. EPSS exploitation probability: 1.81%.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 1.8% exploitation probability (EPSS)

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AnalysisAI

The client_host function in parsers.c in Privoxy before 3.0.24 allows remote attackers to cause a denial of service (invalid read and crash) via an empty HTTP Host header. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-20. The client_host function in parsers.c in Privoxy before 3.0.24 allows remote attackers to cause a denial of service (invalid read and crash) via an empty HTTP Host header. Affected products include: Privoxy. Version information: before 3.0.24.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

DescriptionCVE.org

The client_host function in parsers.c in Privoxy before 3.0.24 allows remote attackers to cause a denial of service (invalid read and crash) via an empty HTTP Host header.

Threat Intelligence Overview

EPSS Score
1.8%
Top 17% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 1.8%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

40
Low Medium High Critical
KEV: 0
EPSS: +2
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)CVE.org

cpe:2.3:a:privoxy:privoxy:*:*:*:*:*:*:*:*
CVE-2013-2503 MEDIUM POC
5.8 Mar 11

Privoxy before 3.0.21 does not properly handle Proxy-Authenticate and Proxy-Authorization headers in the client-server d

CVE-2016-1982 HIGH
7.5 Jan 27

The remove_chunked_transfer_coding function in filters.c in Privoxy before 3.0.24 allows remote attackers to cause a den

CVE-2015-1031 HIGH
7.5 Feb 10

Multiple use-after-free vulnerabilities in Privoxy before 3.0.22 allow remote attackers to have unspecified impact via v

CVE-2021-44542 HIGH
7.5 Dec 23

A memory leak vulnerability was found in Privoxy when handling errors. Rated high severity (CVSS 7.5), this vulnerabilit

CVE-2021-44541 HIGH
7.5 Dec 23

A vulnerability was found in Privoxy which was fixed in process_encrypted_request_headers() by freeing header memory whe

CVE-2021-44540 HIGH
7.5 Dec 23

A vulnerability was found in Privoxy which was fixed in get_url_spec_param() by freeing memory of compiled pattern spec

CVE-2021-20209 HIGH
7.5 May 25

A memory leak vulnerability was found in Privoxy before 3.0.29 in the show-status CGI handler when no action files are c

CVE-2021-20217 HIGH
7.5 Mar 25

A flaw was found in Privoxy in versions before 3.0.31. Rated high severity (CVSS 7.5), this vulnerability is remotely ex

CVE-2021-20216 HIGH
7.5 Mar 25

A flaw was found in Privoxy in versions before 3.0.31. Rated high severity (CVSS 7.5), this vulnerability is remotely ex

CVE-2021-20215 HIGH
7.5 Mar 25

A flaw was found in Privoxy in versions before 3.0.29. Rated high severity (CVSS 7.5), this vulnerability is remotely ex

CVE-2021-20214 HIGH
7.5 Mar 25

A flaw was found in Privoxy in versions before 3.0.29. Rated high severity (CVSS 7.5), this vulnerability is remotely ex

CVE-2021-20213 HIGH
7.5 Mar 25

A flaw was found in Privoxy in versions before 3.0.29. Rated high severity (CVSS 7.5), this vulnerability is remotely ex

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