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CVE-2021-20216

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when...

7.5 HighFix available

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

2.28%Up 1.2 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-20216
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
7.8 HighAV:N/AC:L/Au:N/C:N/I:N/A:C
Weakness
CWE-400, CWE-401
Updated
2026-11-02
CVE List No score

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-20216
Weakness
CWE-400
Updated
2026-11-02
EUVDEUVD-2021-7659 No score

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
EUVD-2021-7659
Updated
2026-11-03
GitHub AdvisoriesGHSA-3429-2hmm-5vvx 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when...

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
GHSA-3429-2hmm-5vvx
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-400, CWE-401
Updated
2026-11-02
OSVALPINE-CVE-2021-20216 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
ALPINE-CVE-2021-20216
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
CVE-2021-20216
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2021-20216 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
DEBIAN-CVE-2021-20216
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-20216 7.5

A flaw was found in Privoxy in versions before 3.0.31. A memory leak that occurs when decompression fails unexpectedly may lead to a denial of service. The highest threat from this vulnerability is to system availability.

Record
UBUNTU-CVE-2021-20216
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2021-0089 No score

Updated privoxy package fixes security vulnerabilities

Fixed a memory leak when decompression fails "unexpectedly". (CVE-2021-20216) Prevent an assertion from getting triggered by a crafted CGI request. (CVE-2021-20217)

Record
MGASA-2021-0089
Updated
2026-11-02
OSVopenSUSE-SU-2021:0265-1 No score

Security update for privoxy

This update for privoxy fixes the following issues:

  • Update to version 3.0.31:
    • Security/Reliability (boo#1181650)
      • Prevent an assertion from getting triggered by a crafted CGI request. Commit 5bba5b89193fa. OVE-20210130-0001. CVE-2021-20217 Reported by: Joshua Rogers (Opera)
      • Fixed a memory leak when decompression fails 'unexpectedly'. Commit f431d61740cc0. OVE-20210128-0001. CVE-2021-20216
    • Bug fixes:
      • Fixed detection of insufficient data for decompression. Previously Privoxy could try to decompress a partly uninitialized buffer.
Record
openSUSE-SU-2021:0265-1
Updated
2026-11-02
OSVopenSUSE-SU-2021:0279-1 No score

Security update for privoxy

This update for privoxy fixes the following issues:

  • Update to version 3.0.31:
    • Security/Reliability (boo#1181650)
      • Prevent an assertion from getting triggered by a crafted CGI request. Commit 5bba5b89193fa. OVE-20210130-0001. CVE-2021-20217 Reported by: Joshua Rogers (Opera)
      • Fixed a memory leak when decompression fails 'unexpectedly'. Commit f431d61740cc0. OVE-20210128-0001. CVE-2021-20216
    • Bug fixes:
      • Fixed detection of insufficient data for decompression. Previously Privoxy could try to decompress a partly uninitialized buffer.

This update was imported from the openSUSE:Leap:15.2:Update update project.

Record
openSUSE-SU-2021:0279-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:11193-1 No score

privoxy-3.0.32-2.3 on GA media

These are all security issues fixed in the privoxy-3.0.32-2.3 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11193-1
Updated
2026-11-02
OSVUSN-4886-1 No score

privoxy vulnerabilities

It was discovered that Privoxy incorrectly handled CGI requests. An attacker could possibly use this issue to cause a denial of service or obtain sensitive information. (CVE-2020-35502, CVE-2021-20209, CVE-2021-20210, CVE-2021-20213, CVE-2021-20215, CVE-2021-20216, CVE-2021-20217, CVE-2021-20272, CVE-2021-20273, CVE-2021-20275)

It was discovered that Privoxy incorrectly handled certain regular expressions. An attacker could possibly use this issue to cause a denial of service or obtain sensitive information. (CVE-2021-20212, CVE-2021-20276)

It was discovered that Privoxy incorrectly handled client tags. An attacker could possibly use this issue to cause Privoxy to consume resources, resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS and Ubuntu 20.10. (CVE-2021-20211)

It was discovered that Privoxy incorrectly handled client tags. An attacker could possibly use this issue to cause Privoxy to consume resources, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 20.10. (CVE-2021-20214)

Record
USN-4886-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
privoxy
Alpine:v3.12
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.13
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.14
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.15
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.16
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.17
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.18
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.19
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.20
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.21
 before 3.0.31-r0
3.0.31-r0
Show 19 moreShow less
Affected packages
PackageAffectedFixed
privoxy
Alpine:v3.22
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.23
 before 3.0.31-r0
3.0.31-r0
privoxy
Alpine:v3.24
 before 3.0.31-r0
3.0.31-r0
privoxy
Debian:12
 before 3.0.31-1
3.0.31-1
privoxy
Debian:13
 before 3.0.31-1
3.0.31-1
privoxy
Debian:14
 before 3.0.31-1
3.0.31-1
privoxy
Debian:9
From an advisory covering 9 CVEs
 before 3.0.26-3+deb9u1, plus listed versions
3.0.26-3
3.0.26-3+deb9u1
privoxy
Mageia:7
From an advisory covering 2 CVEs
 before 3.0.31-1.mga7
3.0.31-1.mga7
privoxy
Ubuntu:Pro:14.04:LTS
 before 3.0.21-7+deb8u1ubuntu0.1~esm1, plus listed versions
3.0.21-13.0.21-23.0.21-7+deb8u1build0.14.04.1
3.0.21-7+deb8u1ubuntu0.1~esm1
privoxy
Ubuntu:16.04:LTS
 before 3.0.24-1ubuntu0.1, plus listed versions
3.0.23-33.0.23-43.0.23-53.0.24-1
3.0.24-1ubuntu0.1
privoxy
Ubuntu:18.04:LTS
 before 3.0.26-5ubuntu0.1, plus listed versions
3.0.26-33.0.26-43.0.26-5
3.0.26-5ubuntu0.1
privoxy
Ubuntu:20.04:LTS
 before 3.0.28-2ubuntu0.1, plus listed versions
3.0.28-2
3.0.28-2ubuntu0.1
privoxy
Ubuntu:Pro:14.04:LTS
From an advisory covering 14 CVEs
 before 3.0.21-7+deb8u1ubuntu0.1~esm1, plus listed versions
3.0.21-13.0.21-23.0.21-7+deb8u1build0.14.04.1
3.0.21-7+deb8u1ubuntu0.1~esm1
privoxy
Ubuntu:16.04:LTS
From an advisory covering 14 CVEs
 before 3.0.24-1ubuntu0.1, plus listed versions
3.0.23-33.0.23-43.0.23-53.0.24-1
3.0.24-1ubuntu0.1
privoxy
Ubuntu:18.04:LTS
From an advisory covering 14 CVEs
 before 3.0.26-5ubuntu0.1, plus listed versions
3.0.26-33.0.26-43.0.26-5
3.0.26-5ubuntu0.1
privoxy
Ubuntu:20.04:LTS
From an advisory covering 14 CVEs
 before 3.0.28-2ubuntu0.1, plus listed versions
3.0.28-2
3.0.28-2ubuntu0.1
privoxy
openSUSE:Leap 15.2
From an advisory covering 2 CVEs
 before 3.0.31-lp152.3.6.1
3.0.31-lp152.3.6.1
privoxy
SUSE:Package Hub 15 SP2
From an advisory covering 2 CVEs
 before 3.0.31-bp152.4.6.1
3.0.31-bp152.4.6.1
privoxy
openSUSE:Tumbleweed
From an advisory covering 7 CVEs
 before 3.0.32-2.3
3.0.32-2.3

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-20216 is a high vulnerability (CVSS 7.5) in Privoxy, published February 5, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.28%, the 83rd percentile. Fixed in privoxy 3.0.31-r0.

References

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