CVE-2021-26906 Denial of service in n/a

What is CVE-2021-26906?

CVE-2021-26906 is a medium-severity denial of service vulnerability in Digium Asterisk, published on 18 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.

Weakness: CWE-404

Which versions are affected by CVE-2021-26906?

It affects 2 products.

Products include Digium Asterisk, Digium Certified Asterisk.

How do I fix CVE-2021-26906?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-26906 being exploited?

There is no known exploitation of CVE-2021-26906 in the wild and no public exploit code.

Other vulnerabilities in Digium Asterisk

• CVE-2017-14100 Command injection in n/a Critical 9.8
• CVE-2014-8418 Privilege escalation in n/a Critical 9.0
• CVE-2011-1599 Missing authorization in n/a Critical 9.0
• CVE-2017-16671 Memory corruption in n/a High 8.8
• CVE-2017-7617 Memory corruption in n/a High 8.8

All Digium Asterisk vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2021-26906, DEBIAN-CVE-2021-26906, GHSA-rjqf-qvfr-v23c.