CVE-2019-18976 Null dereference in n/a

What is CVE-2019-18976?

CVE-2019-18976 is a high-severity vulnerability in Debian Debian Linux, published on 22 Nov 2019. 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_t38.c in Sangoma Asterisk through 13.x and Certified Asterisk through 13.21-x. If it receives a re-invite initiating T.38 faxing and has a port of 0 and no c line in the SDP, a NULL pointer dereference and crash will occur. This is different from CVE-2019-18940.

Weakness: CWE-476

Which versions are affected by CVE-2019-18976?

It affects 3 products.

Products include Debian Debian Linux, Digium Asterisk, Digium Certified Asterisk.

How do I fix CVE-2019-18976?

Apply the vendor's patch.

Is CVE-2019-18976 being exploited?

There is no known exploitation of CVE-2019-18976 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2019-18976, GHSA-6fr3-g4mr-859f, UBUNTU-CVE-2019-18976.