Exploit Released for Unpatched Ubuntu Linux Flaw Enabling Host-Root Container Escape
Unpatched Linux kernel flaw (CVE-2026-80521) enables container escape to host root, with exploit code released for Ubuntu.
A use-after-free vulnerability in the Linux kernel's AF_UNIX socket subsystem (CVE-2026-80521) enables container escape to gain root on the host. The flaw is fixed upstream but unpatched in Ubuntu's 26.04, 24.04, and 22.04 LTS releases, affecting default Docker and Kubernetes environments. Security firm DepthFirst released exploit code for Ubuntu 26.04 after discovering the bug with an AI model, highlighting the growing threat of AI-assisted vulnerability discovery.
- A use-after-free vulnerability (CVE-2026-80521) in the Linux kernel's AF_UNIX socket subsystem allows container escape to host root.
- The flaw is patched upstream but remains unpatched in Ubuntu LTS releases, including cloud versions (AWS, Azure, GCP).
- Security firm DepthFirst released exploit code and found the bug using an AI model for vulnerability detection.
- No confirmed in-the-wild exploitation, but the exploit bypasses container isolation mechanisms.
- CVEs
- CVE-2026-80521
- ATT&CK
- T1611 Escape to Host
- Tags
- ai-vulnerability-discoverycontainer-escapedockerkuberneteslinux-kernelubuntuuse-after-freevulnerability
- Products
- Ubuntu Linux
- Organizations
- DepthFirstOpenAI
- AI models
- dfs-large1
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-80521 | Linux kernel: af_unix: Unlink scc_entry in unix_del_edge(). Kyle Zeng reported that GC could free a dead SCC partially | 7.8 | <1% |
From the original article
3 min read at thehackernews.com
A use-after-free in the Linux kernel's AF_UNIX socket subsystem can be used to escape a container and gain root on the host, security firm DepthFirst said in research published September 22. The flaw, tracked as CVE-2026-80521 (CVSS score: 7. 8), was fixed upstream on August 6, but Ubuntu has not shipped the patch for its 26.
thehackernews.com
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