JPMK (@_JcryPto_)

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Finding the Firecracker bug was only the beginning. With @coinspect, we spent weeks proving a guest could run code in its host-side process, then chained a separate seccomp bypass. The escape is fixed (CVE-2026-122192). Full write-up:

coinspect.com/blog/firecrack…

www.coinspect.com Escaping Firecracker from Guest Userspace Coinspect demonstrated a Firecracker sandbox escape from guest userspace, gained code execution in its host-side process, and used a second issue to bypass Firecracker's...

JPMK @_JcryPto_ 4d

People are asking how you corrupt memory in a sandbox written in Rust. 🦀🔥

The spark came from an unsafe block: mmap(MAP_FIXED) failed after unmapping a guest-RAM page. KVM kept pointing there; Firecracker reused it. Guest writes became VMM writes. 🏴‍☠️

JPMK @_JcryPto_ 4d

Congrats on PwnEscape! It shows a guest-to-host route through a guest accessible kernel flaw. Our work adds a different route: a vulnerability in Firecracker itself let the guest userspace reach VMM control under the stock jailer, without kernel CVE as the entry point. coinspect.com/blog/firecrack…

www.coinspect.com Escaping Firecracker from Guest Userspace Coinspect demonstrated a Firecracker sandbox escape from guest userspace, gained code execution in its host-side process, and used a second issue to bypass Firecracker's...

PWN AI @pwn_ai 4d

Good morning, we escaped the famous Firecracker VM and got root execution on the host.

Full firecracker escape technical writeup and Proof of Concept code attached below.

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JPMK @_JcryPto_ 5d

boomer time!

Coinspect Security Verified account @coinspect 5d

We escaped AWS Firecracker. 🔥

We discovered a VM isolation vulnerability affecting versions 0.23.0–1.16.1 when restoring snapshots using the File memory backend with balloon or virtio-mem devices.

Fixed in 1.16.2 and 1.17.0+ (CVE-2026-122192)

Technical write-up:
coinspect.com/blog/firecrack…
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JPMK @_JcryPto_ 5d

old school fun times

Juliano Rizzo @julianor 5d

Reporting bugs to big vendors is as frustrating and demotivating as ever. This is one human side of security that AI hasn't improved.
Let me tell you why human researchers still matter:
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JPMK

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