CVE-2021-20276: A flaw was found in privoxy before 3.0.32

Q: How do I fix CVE-2021-20276?

privoxy: upgrade to 3.0.32; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-20276 being exploited?

CVE-2021-20276 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-2021-20276 affect?

CVE-2021-20276 affects privoxy, debian linux. Severity is high (CVSS 7.5). A flaw was found in privoxy before 3.0.32. Invalid memory access with an invalid pattern passed to pcre_compile() may lead to denial of service.

Q: How urgent is CVE-2021-20276?

Priority 56/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2021-20276 is a high-severity flaw (CVSS 7.5) affecting privoxy, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in privoxy before 3.0.32. Invalid memory access with an invalid pattern passed to pcre_compile() may lead to denial of service.

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

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	2.0% (top 20%)
CISA exploited list	No
Weakness	CWE-119
Published	2021-03-09
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2021-03-09 14:15 UTCPublished CVE record published
2026-06-17 03:33 UTCUpdated Record last modified

privoxy privoxy UPGRADE

Affected: < 3.0.32

Fixed in: 3.0.32

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.0.32 (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.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-20276?

privoxy: upgrade to 3.0.32; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-20276 being exploited?

CVE-2021-20276 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-2021-20276 affect?

CVE-2021-20276 affects privoxy, debian linux. Severity is high (CVSS 7.5). A flaw was found in privoxy before 3.0.32. Invalid memory access with an invalid pattern passed to pcre_compile() may lead to denial of service.

How urgent is CVE-2021-20276?

Priority 56/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

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-2021-20275 HIGH 7.5 UPGRADE MITIGATE A flaw was found in privoxy before 3.0.32

References

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