CVE-2017-16943 Use after free in n/a

What is CVE-2017-16943?

CVE-2017-16943 is a critical use after free vulnerability in Debian Debian Linux, published on 25 Nov 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via vectors involving BDAT commands.

Weakness: CWE-416

Which versions are affected by CVE-2017-16943?

It affects 2 products.

Products include Debian Debian Linux, Exim Exim.

How do I fix CVE-2017-16943?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2017-16943 being exploited?

There is no known exploitation of CVE-2017-16943 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

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 CLEANSTART-2025-UH23278, DEBIAN-CVE-2017-16943, GHSA-6pmg-h497-cq5q.