How severe is CVE-2021-43804?

CVE-2021-43804 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-43804 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43804?

CVE-2021-43804 primarily affects Teluu Pjsip. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-43804?

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-2021-43804 published?

CVE-2021-43804 was published on 2021-12-22 and last updated on 2026-06-17.

CVE-2021-43804

CVE-2021-43804 is a high-severity vulnerability in Teluu Pjsip with a CVSS 3.x base score of 7.3. 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-125.

Key facts

Severity: High (CVSS 3.x base score 7.3)
CVSS v2: 7.5
EPSS exploit prediction: 2% (80th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Teluu Pjsip
Published: 2021-12-22
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-43804?: 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.
How severe is CVE-2021-43804?: CVE-2021-43804 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-43804 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43804?: CVE-2021-43804 primarily affects Teluu Pjsip. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-43804?: 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-2021-43804 published?: CVE-2021-43804 was published on 2021-12-22 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:teluu:pjsip:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

More vulnerabilities in Teluu Pjsip

CVE-2023-38703 — Critical (CVSS 9.8): PJSIP is a free and open source multimedia communication library written in C with high level API in C, C++, Java, C#,…
CVE-2022-31031 — Critical (CVSS 9.8): PJSIP is a free and open source multimedia communication library written in C language implementing standard based…
CVE-2021-43303 — Critical (CVSS 9.8): Buffer overflow in PJSUA API when calling pjsua_call_dump. An attacker-controlled 'buffer' argument may cause a buffer…
CVE-2021-43301 — Critical (CVSS 9.8): Stack overflow in PJSUA API when calling pjsua_playlist_create. An attacker-controlled 'file_names' argument may cause…
CVE-2021-43300 — Critical (CVSS 9.8): Stack overflow in PJSUA API when calling pjsua_recorder_create. An attacker-controlled 'filename' argument may cause a…
CVE-2021-43299 — Critical (CVSS 9.8): Stack overflow in PJSUA API when calling pjsua_player_create. An attacker-controlled 'filename' argument may cause a…

All CVEs affecting Teluu Pjsip →

Other CWE-125 (Out-of-bounds Read) vulnerabilities

CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →