CVE-2017-1000405
Nevertheless, it does allow us to overwrite read-only huge pages.
Does this matter?
2 public exploits are published in Exploit-DB and the impact is high, while EPSS rates exploitation at 2.8%. Anyone can run this; patch or mitigate before the next change window and check exposed instances for signs of use.
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.
- CVSS 3.1
- 7.0 HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 2.84% probability · 87th percentile
- Public exploits
- 2 in Exploit-DB · first 30 November 2017
- CISA KEV
- Not listed
- Weakness
- CWE-362
- Affected
- linux/linux kernel
- Source
- cve@mitre.org
EPSS 2.8% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (2)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://www.securityfocus.com/bid/102032Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040020Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:0180Third Party Advisory
- https://medium.com/bindecy/huge-dirty-cow-cve-2017-1000405-110eca132de0Exploit, Issue Tracking, Third Party Advisory
- https://source.android.com/security/bulletin/pixel/2018-02-01Third Party Advisory
- https://www.exploit-db.com/exploits/43199/Exploit, Issue Tracking, Third Party Advisory, VDB Entry
- http://www.securityfocus.com/bid/102032Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040020Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:0180Third Party Advisory
- https://medium.com/bindecy/huge-dirty-cow-cve-2017-1000405-110eca132de0Exploit, Issue Tracking, Third Party Advisory
- https://source.android.com/security/bulletin/pixel/2018-02-01Third Party Advisory
- https://www.exploit-db.com/exploits/43199/Exploit, Issue Tracking, Third Party Advisory, VDB Entry
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.