How severe is CVE-2021-20209?

CVE-2021-20209 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-2021-20209 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20209?

CVE-2021-20209 affects Privoxy. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-20209?

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-2021-20209 published?

CVE-2021-20209 was published on 2021-05-25 and last updated on 2026-06-17.

CVE-2021-20209

CVE-2021-20209 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-401.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Privoxy
Published: 2021-05-25
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2021-20209?: A memory leak vulnerability was found in Privoxy before 3.0.29 in the show-status CGI handler when no action files are configured.
How severe is CVE-2021-20209?: CVE-2021-20209 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-2021-20209 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20209?: CVE-2021-20209 affects Privoxy. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-20209?: 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-2021-20209 published?: CVE-2021-20209 was published on 2021-05-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:privoxy:privoxy:*:*:*:*:*:*:*:*

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