$ cve CVE-2017-1000405 JSON

CVE-2017-1000405 EXPLOIT

7.0

HIGH · CVSS 3.1 · EPSS 2.8% (pctl 86)

Patch early

A public exploit exists.

Description

The Linux Kernel versions 2.6.38 through 4.14 have a problematic use of pmd_mkdirty() in the touch_pmd() function inside the THP implementation. touch_pmd() can be reached by get_user_pages(). In such case, the pmd will become dirty. This scenario breaks the new can_follow_write_pmd()'s logic - pmd can become dirty without going through a COW cycle. This bug is not as severe as the original "Dirty cow" because an ext4 file (or any other regular file) cannot be mapped using THP. Nevertheless, it does allow us to overwrite read-only huge pages. For example, the zero huge page and sealed shmem files can be overwritten (since their mapping can be populated using THP). Note that after the first write page-fault to the zero page, it will be replaced with a new fresh (and zeroed) thp.

Scoring

CVSS	7.0 (HIGH, v3.1)
Vector	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS	2.84% — more likely to be exploited than 86% of all CVEs
Weakness	CWE-362
On CISA KEV	no
Public exploit	yes
Published	2017-11-30
Last modified	2026-06-17

Affected (1)

Vendor	Product
linux	linux kernel

Public exploits

Source	Title	Date
exploit-db	Linux Kernel - 'The Huge Dirty Cow' Overwriting The Huge Zero Page (2)	2017-12-11
exploit-db	Linux Kernel - 'The Huge Dirty Cow' Overwriting The Huge Zero Page (1)	2017-11-30

References

→ the Explorer · watch your stack · NVD