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Last updated: May 14, 2026 at 10:49 AM UTC
All 219 Vulnerability 76 Breach 45 Threat 91 Defense 7
Tag: container-escape (4 articles)Clear

9-year-old Linux kernel bug 'Copy Fail' lets any user with shell access become root in seconds - works on every major distribution since 2017 (CVE-2026-31431)

Researchers at Theori and Xint disclosed Copy Fail yesterday, a Linux kernel bug introduced in 2017 that lets any unprivileged user with shell access become root in seconds. The exploit is a 732-byte Python script that works without version-specific tweaks on every major Linux distribution since 2017 - Ubuntu, Amazon Linux, RHEL, SUSE. Unlike previous kernel bugs (Dirty Cow, Dirty Pipe), Copy Fail has no race condition and no per-kernel offsets. It also leaves no trace on disk because it only modifies the in-memory page cache. The bug was found using AI-assisted reverse engineering and has been hiding in the open for nearly nine years.

Check
Update the kernel on every Linux server, container host, and CI runner you operate today, especially anything that runs untrusted code or hosts multiple tenants.
Affected
Every Linux distribution since 2017 with kernel 4.14 or later. CVE-2026-31431, CVSS 7.8. Acute risk: shared-kernel multi-tenant environments (Kubernetes nodes, Docker hosts), CI/CD runners that execute untrusted PR code (GitHub Actions self-hosted, GitLab runners, Jenkins agents), notebook hosts, and anything using Linux containers as a security boundary. Firecracker microVMs and gVisor are not affected.
Fix
Apply the kernel update from your distribution that includes commit a664bf3d603d. Until patched, blacklist the algif_aead module: 'echo "install algif_aead /bin/false" > /etc/modprobe.d/disable-algif.conf' then 'rmmod algif_aead'. The disable does not break dm-crypt, kTLS, IPsec, or SSH. For multi-tenant Kubernetes clusters, treat container boundaries as broken until patched.

Cohere's Terrarium AI code sandbox has a root-level escape with no patch coming (CVE-2026-5752, CVSS 9.3)

A critical sandbox-escape flaw in Cohere AI's open-source Terrarium project lets code running inside the sandbox break out and execute arbitrary commands as root on the host Node.js process. Terrarium is a Python sandbox built on Pyodide (a browser- and Node.js-compatible Python distribution running in WebAssembly) and deployed as a Docker container to safely run untrusted code submitted by users or generated by a large language model. That exact use case makes the blast radius real: any AI product using Terrarium to evaluate LLM-generated Python code is giving its models a direct path to root on the container and, from there, potentially on the host. The flaw (CVE-2026-5752, CVSS 9.3) stems from JavaScript prototype chain traversal in the Pyodide WebAssembly environment: sandboxed code can reach parent and global object prototypes to manipulate objects in the host, a technique SentinelOne describes as prototype pollution bypassing the intended security boundaries. Exploitation needs local access to the sandbox but no special privileges or user interaction. The project has been starred 312 times and forked 56 times. Because Cohere is no longer actively maintaining Terrarium, the flaw is unlikely to ever be patched. Security researcher Jeremy Brown reported the issue.

Check
Search your AI and data-engineering stack for any use of Cohere's Terrarium (direct or as a dependency or fork) and identify whether user-submitted or LLM-generated code is routed through it.
Affected
All versions of Cohere AI Terrarium and any fork that inherits the Pyodide prototype traversal issue. The project is unmaintained - no patched version will be published.
Fix
Stop accepting user- or LLM-submitted code into Terrarium sandboxes. CERT/CC advises disabling any feature that submits code to Terrarium, segmenting the network so a compromised container cannot reach other services, restricting container and orchestrator access to authorized personnel, and deploying a WAF to block exploitation patterns. The only durable fix is to migrate off Terrarium to a maintained sandbox (gVisor, Firecracker, or a commercially supported code-execution service) with per-request ephemeral VMs and strict egress controls.

Cohere's Terrarium AI sandbox breaks out to root on the host with no vendor patch in sight (CVE-2026-5752)

CERT Coordination Center disclosed CVE-2026-5752, a CVSS 9.3 sandbox escape in Cohere's open source Terrarium, a Python sandbox that runs on Pyodide (a WebAssembly Python distribution for Node.js) and is used to execute untrusted or LLM-generated code inside a Docker container. The flaw lets code running inside the Pyodide sandbox traverse the JavaScript prototype chain to reach the host Node.js Function constructor, compile arbitrary JavaScript in the host realm, and execute it as root inside the container. From that point attackers can read /etc/passwd and environment variables, reach other services on the container network, and attempt a further container escape. Critically, CERT/CC notes it was unable to coordinate a patch with Cohere, so no fix has shipped. Terrarium has 312 GitHub stars and 56 forks - a moderate audience, but anyone running it is a poster-child target for prompt-injection attacks that instruct the LLM to emit sandbox-breaking code. The underlying prototype-chain traversal pattern is the same technique seen in January's CVE-2026-22686 against the enclave-vm sandbox.

Check
If you run Terrarium anywhere in your stack (including behind an AI product that evaluates user-supplied Python) take it offline until you can wrap it in a second isolation layer or replace it with a hardened alternative.
Affected
All currently-available versions of Cohere Terrarium (github.com/cohere-ai/cohere-terrarium). The JavaScript prototype-chain traversal in Pyodide WebAssembly is exploitable by any code the sandbox accepts for execution - including code an LLM generates from a user prompt, which is the entire point of the product. CERT/CC confirmed there is no vendor patch as of the advisory.
Fix
Disable any feature that lets users (or an upstream LLM) submit arbitrary code to Terrarium. Wrap Terrarium deployments in a second isolation layer - gVisor or Firecracker microVMs for stronger kernel isolation, strict network egress policies, read-only root filesystems, and dropped Linux capabilities including CAP_SYS_ADMIN. Segment Terrarium containers so they cannot reach internal APIs, databases, or metadata services. Monitor for unexpected root-level process creation inside Terrarium containers and alert on any Node.js Function constructor invocation originating from sandbox code. For new AI-code-execution use cases, evaluate alternatives like the Deno-based approach with explicit permission flags or E2B's hardened cloud sandboxes.

Docker Engine authorization bypass lets attackers escape containers and access host credentials (CVE-2026-34040)

A high-severity Docker Engine flaw allows attackers to bypass authorization plugins with a single oversized HTTP request. CVE-2026-34040 (CVSS 8.8) stems from an incomplete fix for CVE-2024-41110 from July 2024 - the original patch missed requests over 1MB, which get forwarded to the Docker daemon without their body, so the AuthZ plugin sees nothing to block while the daemon processes the full malicious payload. The result: a privileged container with root access to the host filesystem, exposing AWS credentials, SSH keys, Kubernetes configs, and everything else on the machine. Critically, Cyera researchers demonstrated that AI coding agents running inside Docker sandboxes can be tricked via prompt injection into crafting the bypass request themselves - no human attacker needed.

Check
Check if you use Docker with authorization plugins (OPA, Prisma Cloud, or custom AuthZ policies). If you don't use AuthZ plugins, you're not affected by this specific flaw.
Affected
Docker Engine versions prior to 29.3.1 when running with AuthZ plugins enabled. The underlying flaw has existed since Docker Engine 1.10. Environments running AI agents or developer tools inside Docker containers are at elevated risk.
Fix
Update Docker Engine to version 29.3.1. If you can't patch immediately: avoid AuthZ plugins that rely on request body inspection, restrict Docker API access to trusted parties only, or run Docker in rootless mode so that even a privileged container maps to an unprivileged host UID. For AI agent sandboxes, apply the --userns-remap setting to limit blast radius.