CVE-2021-20274

A flaw was found in privoxy before 3.0.32. A crash may occur due a NULL-pointer dereference when the socks server misbehaves.

Published: 2021-03-09 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20274 is rated Moderate Risk (58.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.92%). EPSS rose +1.38% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-20274

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.54% 1.92% +1.38%
2 2026-05-27 0.69% 0.54% -0.16%
3 2025-11-21 — 0.69% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20274

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-20274

OS Trackers for CVE-2021-20274

vendor priority summary link
alpine high CVE-2021-20274: 1 source package rows (privoxy); 20 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 8, open 12. https://security.alpinelinux.org/vuln/CVE-2021-20274
debian not yet assigned CVE-2021-20274 not yet assigned priority: Debian including 1 source packages (privoxy), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-20274
gentoo normal CVE-2021-20274: 1 GLSA(s) (202107-16), 1 atom(s) (net-proxy/privoxy); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-20274
ubuntu medium CVE-2021-20274 medium priority: Ubuntu including 1 source packages (privoxy), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): not-affected 5, released 1. https://ubuntu.com/security/CVE-2021-20274

Affected software / configurations for CVE-2021-20274

Vendor Product Version Raw CPE
privoxy privoxy < 3.0.32 cpe:2.3:a:privoxy:privoxy:*:*:*:*:*:*:*:*

References for CVE-2021-20274

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1936662 Issue Tracking Patch Third Party Advisory
https://security.gentoo.org/glsa/202107-16 Third Party Advisory
https://www.privoxy.org/announce.txt Release Notes Vendor Advisory
cvelogic Threat Intelligence