How severe is CVE-2021-21375?

CVE-2021-21375 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-21375 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21375?

CVE-2021-21375 primarily affects Teluu Pjsip. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21375?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-21375 published?

CVE-2021-21375 was published on 2021-03-10 and last updated on 2026-06-17.

CVE-2021-21375

CVE-2021-21375 is a medium-severity vulnerability in Teluu Pjsip with a CVSS 3.x base score of 6.5. 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-754.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-754
Affected product: Teluu Pjsip
Published: 2021-03-10
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 PJSIP version 2.10 and earlier, after an initial INVITE has been sent, when two 183 responses are received, with the first one causing negotiation failure, a crash will occur. This results in a denial of service.

Frequently asked questions

What is CVE-2021-21375?: 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 PJSIP version 2.10 and earlier, after an initial INVITE has been sent, when two 183 responses are received, with the first one causing negotiation failure, a crash will occur. This results in a denial of service.
How severe is CVE-2021-21375?: CVE-2021-21375 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-21375 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21375?: CVE-2021-21375 primarily affects Teluu Pjsip. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21375?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21375 published?: CVE-2021-21375 was published on 2021-03-10 and last updated on 2026-06-17.

References

Affected products (2)

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

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-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities

CVE-2026-24054 — Critical (CVSS 10.0): Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs)…
CVE-2021-0211 — Critical (CVSS 10.0): An improper check for unusual or exceptional conditions in Juniper Networks Junos OS and Junos OS Evolved Routing…
CVE-2026-8091 — Critical (CVSS 9.8): Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150,…
CVE-2024-52316 — Critical (CVSS 9.8): Unchecked Error Condition vulnerability in Apache Tomcat. If Tomcat is configured to use a custom Jakarta…
CVE-2024-7826 — Critical (CVSS 9.8): Improper Check for Unusual or Exceptional Conditions vulnerability in Webroot SecureAnywhere - Web Shield on Windows,…
CVE-2023-37303 — Critical (CVSS 9.8): An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to…

Browse all CWE-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities →