How severe is CVE-2021-20273?

CVE-2021-20273 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-20273 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20273?

CVE-2021-20273 primarily affects Privoxy. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20273?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-20273 published?

CVE-2021-20273 was published on 2021-03-09 and last updated on 2026-06-17.

CVE-2021-20273

CVE-2021-20273 is a high-severity vulnerability in Privoxy with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Privoxy
Published: 2021-03-09
Last modified: 2026-06-17

Description

A flaw was found in privoxy before 3.0.32. A crash can occur via a crafted CGI request if Privoxy is toggled off.

Frequently asked questions

What is CVE-2021-20273?: A flaw was found in privoxy before 3.0.32. A crash can occur via a crafted CGI request if Privoxy is toggled off.
How severe is CVE-2021-20273?: CVE-2021-20273 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-20273 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20273?: CVE-2021-20273 primarily affects Privoxy. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20273?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-20273 published?: CVE-2021-20273 was published on 2021-03-09 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:privoxy:privoxy:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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