CVE-2021-20210: A flaw was found in Privoxy in versions before 3.0.29

Q: How do I fix CVE-2021-20210?

privoxy: upgrade to 3.0.29. Exact commands for each OS are on this page.

Q: Is CVE-2021-20210 being exploited?

CVE-2021-20210 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-20210 affect?

CVE-2021-20210 affects privoxy. Severity is high (CVSS 7.5). A flaw was found in Privoxy in versions before 3.0.29. Memory leak in the show-status CGI handler when no filter files are configured can lead to a system crash.

Q: How urgent is CVE-2021-20210?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2021-20210 is a high-severity flaw (CVSS 7.5) affecting privoxy. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in Privoxy in versions before 3.0.29. Memory leak in the show-status CGI handler when no filter files are configured can lead to a system crash.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-401
Published	2021-03-25
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: privoxy

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-03-25 19:15 UTCPublished CVE record published
2026-06-17 03:33 UTCUpdated Record last modified

privoxy privoxy UPGRADE

Affected: < 3.0.29

Fixed in: 3.0.29

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy privoxy || rpm -q privoxy || privoxy --version

2. UPGRADE to 3.0.29 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade privoxy

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade privoxy

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-20210?

privoxy: upgrade to 3.0.29. Exact commands for each OS are on this page.

Is CVE-2021-20210 being exploited?

CVE-2021-20210 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-20210 affect?

CVE-2021-20210 affects privoxy. Severity is high (CVSS 7.5). A flaw was found in Privoxy in versions before 3.0.29. Memory leak in the show-status CGI handler when no filter files are configured can lead to a system crash.

How urgent is CVE-2021-20210?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-44543 MEDIUM 6.1 UPGRADE An XSS vulnerability was found in Privoxy which was fixed in cgi_error_no_template() by encode the template na
CVE-2021-44542 HIGH 7.5 UPGRADE A memory leak vulnerability was found in Privoxy when handling errors.
CVE-2021-44541 HIGH 7.5 UPGRADE A vulnerability was found in Privoxy which was fixed in process_encrypted_request_headers() by freeing header
CVE-2021-44540 HIGH 7.5 UPGRADE A vulnerability was found in Privoxy which was fixed in get_url_spec_param() by freeing memory of compiled pat
CVE-2021-20276 HIGH 7.5 UPGRADE MITIGATE A flaw was found in privoxy before 3.0.32

References

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