Vulnerability identifier: #VU55286

Vulnerability risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-31878

CWE-ID: CWE-399

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Asterisk Open Source
Server applications / Conferencing, Collaboration and VoIP solutions

Vendor: Digium (Linux Support Services)

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper management of internal resources within the application in PJSIP channel driver in res_pjsip_session.c. A remote user can send a re-INVITE message without SDP after Asterisk has sent a BYE request and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Asterisk Open Source: 18.3.0 - 18.5.0 rc1, 16.17.0 rc1 - 16.19.0 rc1

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External links
http://downloads.asterisk.org/pub/security/AST-2021-007.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.