EIP-2026-102636

PRE-CVE

Linux - 'userfaultfd' Bypasses tmpfs File Permissions

Title source: legacy
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for EIP-2026-102636. PoCs published by Google Security Research.

AI-analyzed exploit summary The exploit demonstrates a vulnerability in the Linux kernel's userfaultfd API, allowing a user with read-only access to a tmpfs file to write data into holes in the file. The proof-of-concept code registers a userfaultfd region for a read-only shared mapping and uses the UFFDIO_COPY ioctl to write data into the file, bypassing the read-only restriction.

Description

Linux - 'userfaultfd' Bypasses tmpfs File Permissions

Exploits (1)

exploitdb WORKING POC VERIFIED
by Google Security Research · textdoslinux
https://www.exploit-db.com/exploits/45983

The exploit demonstrates a vulnerability in the Linux kernel's userfaultfd API, allowing a user with read-only access to a tmpfs file to write data into holes in the file. The proof-of-concept code registers a userfaultfd region for a read-only shared mapping and uses the UFFDIO_COPY ioctl to write data into the file, bypassing the read-only restriction.

Classification
Working Poc 100%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: Linux kernel (userfaultfd API)
No auth needed
Prerequisites: Read-only access to a tmpfs file with holes · userfaultfd API support in the kernel
devstral-2 · analyzed Feb 18, 2026 Full analysis →

Details

Status pre_cve
Tracked Since Feb 18, 2026