Is CVE-2018-20721 in the CISA KEV catalog?

No. CVE-2018-20721 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2018-20721?

CVE-2018-20721 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2018-20721?

CVE-2018-20721 has an EPSS score of 2.05% (79th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2018-20721?

Upgrade uriparser on debian 11 to 0.9.1-1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2018-20721

CRITICALEPSS 79th pctl

9.8

CVSS v3

NVD

Description

URI_FUNC() in UriParse.c in uriparser before 0.9.1 has an out-of-bounds read (in uriParse*Ex* functions) for an incomplete URI with an IPv6 address containing an embedded IPv4 address, such as a "//[::44.1" address.

CWE-125Out-of-bounds Read

How to fix

Remediation Available

uriparserDebian

Fixed in:0.9.1-1CVE-2018-20721

liburiparser1Ubuntu

Fixed in:0.7.5-1ubuntu2+esm2USN-5172-2

Fixed in:0.8.4-1ubuntu0.16.04.1~esm2USN-5172-2

Fixed in:0.8.4-1+deb9u2build0.18.04.1USN-5172-1

uriparserUbuntu

Fixed in:0.7.5-1ubuntu2+esm2USN-5172-2

Fixed in:0.8.4-1ubuntu0.16.04.1~esm2USN-5172-2

Fixed in:0.8.4-1+deb9u2build0.18.04.1USN-5172-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

2.05%probability of exploitation in 30 days

79thpercentile

Elevated risk: more likely to be exploited than 79% of all known CVEs.

References

Patch1

github.com

Third-Party Advisory3

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0160	High	7.5	100%	KEV	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2021-4034	High	7.8	95%	KEV	Fix
CVE-2023-21769	High	7.5	92%	-	Fix
CVE-2023-49285	High	8.6	89%	-	Fix
CVE-2020-8794	Critical	9.8	89%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.