Firecracker MicroVM Escape Allows Root Code Execution on Host
Original title: Firecracker VM Escape: PwnEscape Part 2
Researchers escape Firecracker microVM and achieve root code execution on the host by modifying saved registers in pt_regs.
Firecracker is a lightweight virtual machine monitor that keeps untrusted code inside a microVM. The researchers escaped the microVM and achieved code execution as root on the host. They found how it saved registers, changed where it would resume, and made it execute a call of their choosing when it returned from KVM. The guest then restored the temporary stack changes. Firecracker kept running, and the VM remained accessible over SSH.
Unconfirmed: CVE-2026-99999 claimed but not confirmed in the wild
- VM escape via pt_regs modification on KVM return
- Located guest page using nonce and EPT translation
- Identified Firecracker process using reverse page table mapping
- Used load bias to find exploit code in Firecracker binary
- CVE-2026-99999
- CVEs
- CVE-2026-99999
- Vendors
- Firecracker
- Products
- Firecracker microVM
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-99999 | Linux kernel IPv4 checksum metadata can corrupt headers | 9.3 | <1% | PoC ×10 |
From the original article
10 min read at pwn.ai
Firecracker is supposed to keep untrusted code inside a microVM. We escaped it and achieved code execution as root on the host. We found how it saved registers, changed where it would resume, and made it execute a call of our choosing when it returned from KVM.
By pwn.ai via atmosx · pwn.ai
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