Is CVE-2021-43804 in the CISA KEV catalog?

No. CVE-2021-43804 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-43804?

CVE-2021-43804 has a CVSS v3 base score of 7.3 (HIGH).

What is the EPSS score for CVE-2021-43804?

CVE-2021-43804 has an EPSS score of 2.19% (80th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-43804?

Upgrade asterisk on debian 11 to 1:16.28.0~dfsg-0+deb11u1 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2021-43804

HIGHEPSS 80th pctl

7.3

CVSS v3

NVD

Description

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In affected versions if the incoming RTCP BYE message contains a reason's length, this declared length is not checked against the actual received packet size, potentially resulting in an out-of-bound read access. This issue affects all users that use PJMEDIA and RTCP. A malicious actor can send a RTCP BYE message with an invalid reason length. Users are advised to upgrade as soon as possible. There are no known workarounds.

CWE-125Out-of-bounds Read

How to fix

Remediation Available

asteriskDebian

Fixed in:1:16.28.0~dfsg-0+deb11u1CVE-2021-43804

Fixed in:1:18.12.0~dfsg+~cs6.12.40431413-1CVE-2021-43804

jamiUbuntu

Fixed in:20190215.1.f152c98~ds1-1+deb10u2build0.20.04.1USN-6422-1

Fixed in:20230206.0~ds1-5ubuntu0.1USN-6422-1

jami-daemonUbuntu

Fixed in:20190215.1.f152c98~ds1-1+deb10u2build0.20.04.1USN-6422-1

Fixed in:20230206.0~ds1-5ubuntu0.1USN-6422-1

ringUbuntu

Fixed in:20180228.1.503da2b~ds1-1ubuntu0.1~esm1USN-6422-1

Fixed in:20190215.1.f152c98~ds1-1+deb10u2build0.20.04.1USN-6422-1

Fixed in:20230206.0~ds1-5ubuntu0.1USN-6422-1

ring-daemonUbuntu

Fixed in:20180228.1.503da2b~ds1-1ubuntu0.1~esm1USN-6422-1

Fixed in:20190215.1.f152c98~ds1-1+deb10u2build0.20.04.1USN-6422-1

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

ConfidentialityLow

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

2.19%probability of exploitation in 30 days

80thpercentile

Elevated risk: more likely to be exploited than 80% of all known CVEs.

References

Patch2

Third-Party Advisory4

Other references2

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 2025-11-04.