CVE-2026-76921 Use After Free in Wireshark
A use-after-free flaw in the CMS protocol dissector allows attackers to cause a denial of service via crafted packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-76921?
CVE-2026-76921 is a medium-severity use after free vulnerability in Wireshark Wireshark, published on 19 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
CMS protocol dissector crash in 4.6.0 to 4.6.7 and 4.4.0 to 4.4.18 allows denial of service
Weakness: CWE-416
Which versions are affected by CVE-2026-76921?
It affects 1 product.
Products include Wireshark Wireshark.
How do I fix CVE-2026-76921?
Upgrade to a fixed version.
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-2026-76921 being exploited?
There is no known exploitation of CVE-2026-76921 in the wild and no public exploit code.
Other vulnerabilities in Wireshark Wireshark
Sources
Also known as AZL-96930, DEBIAN-CVE-2026-76921, GHSA-rg88-p8vc-vr4m, MINI-6c6q-v45x-hx7h, UBUNTU-CVE-2026-76921.