HOME VULNERABILITIESCVE-2021-37706

CRITICAL

CVE-2021-37706

CWE-191Published: December 22, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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 STUN message contains an ERROR-CODE attribute, the header length is not checked before performing a subtraction operation, potentially resulting in an integer underflow scenario. This issue affects all users that use STUN. A malicious actor located within the victim’s network may forge and send a specially crafted UDP (STUN) message that could remotely execute arbitrary code on the victim’s machine. Users are advised to upgrade as soon as possible. There are no known workarounds.

Technical Analysis

CVE-2021-37706 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

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

Affected Vendors & Products

asterisk1 product(s)

certified asterisk

Debian1 product(s)

debian linux

sangoma1 product(s)

asterisk

teluu1 product(s)

pjsip

Source: NVD CPE · 6 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttp://seclists.org/fulldisclosure/2022/Mar/0

PATCHhttps://github.com/pjsip/pjproject/commit/15663e3f37091069b8c98a7fce680dc04bc8e865

PATCHhttps://github.com/pjsip/pjproject/security/advisories/GHSA-2qpg-f6wf-w984

PATCHhttp://seclists.org/fulldisclosure/2022/Mar/0

PATCHhttps://github.com/pjsip/pjproject/commit/15663e3f37091069b8c98a7fce680dc04bc8e865

PATCHhttps://github.com/pjsip/pjproject/security/advisories/GHSA-2qpg-f6wf-w984

ADVISORYhttp://packetstormsecurity.com/files/166225/Asterisk-Project-Security-Advisory-AST-2022-004.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/03/msg00035.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/11/msg00021.html

ADVISORYhttps://security.gentoo.org/glsa/202210-37

ADVISORYhttps://www.debian.org/security/2022/dsa-5285

ADVISORYhttp://packetstormsecurity.com/files/166225/Asterisk-Project-Security-Advisory-AST-2022-004.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/03/msg00035.html

ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/11/msg00021.html

ADVISORYhttps://security.gentoo.org/glsa/202210-37

ADVISORYhttps://www.debian.org/security/2022/dsa-5285

All References (19)

→

http://packetstormsecurity.com/files/166225/Asterisk-Project-Security-Advisory-AST-2022-004.htmlThird Party Advisory · VDB Entry

→

http://seclists.org/fulldisclosure/2022/Mar/0Mailing List · Patch · Third Party Advisory

→

https://github.com/pjsip/pjproject/commit/15663e3f37091069b8c98a7fce680dc04bc8e865Patch · Third Party Advisory

→

https://github.com/pjsip/pjproject/security/advisories/GHSA-2qpg-f6wf-w984Patch · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2022/03/msg00035.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2022/11/msg00021.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2023/08/msg00038.html

→

https://security.gentoo.org/glsa/202210-37Third Party Advisory

→

https://www.debian.org/security/2022/dsa-5285Third Party Advisory

→

http://packetstormsecurity.com/files/166225/Asterisk-Project-Security-Advisory-AST-2022-004.htmlThird Party Advisory · VDB Entry

→

http://seclists.org/fulldisclosure/2022/Mar/0Mailing List · Patch · Third Party Advisory

→

https://github.com/pjsip/pjproject/commit/15663e3f37091069b8c98a7fce680dc04bc8e865Patch · Third Party Advisory

→

https://github.com/pjsip/pjproject/security/advisories/GHSA-2qpg-f6wf-w984Patch · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2022/03/msg00035.htmlMailing List · Third Party Advisory

→

https://lists.debian.org/debian-lts-announce/2022/11/msg00021.htmlMailing List · Third Party Advisory

Quick Facts

CVE IDCVE-2021-37706

CVSS Score9.8 / 10

SeverityCRITICAL

WeaknessCWE-191

CISA KEVNo

Affected4 vendor(s)

PublishedDec 22, 2021

Related CVEs (CWE-191)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2021-37706 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

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