Description
The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles access control for certain UFFDIO_ ioctl calls, as demonstrated by allowing local users to write data into holes in a tmpfs file (if the user has read-only access to that file, and that file contains holes), related to fs/userfaultfd.c and mm/userfaultfd.c.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 4.19.9-1 | — |
| Debian 13 | linux | 4.19.9-1 | — |
| Debian 12 | linux | 4.19.9-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | linux | 4.15.0-46.49 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1033.35 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-azure | 4.18.0-1013.13~18.04.1 | USN-3903-2 |
| Ubuntu 18.04 LTS | linux-gcp | 4.15.0-1028.29 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-gcp-edge | 4.18.0-1007.8~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-hwe | 4.18.0-16.17~18.04.1 | USN-3903-2 |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1030.30 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1034.39 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1009.11 | USN-3901-1 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1032.34 | USN-3901-1 |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1033.35~16.04.1 | USN-3901-2 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1040.44 | USN-3901-2 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1028.29~16.04.1 | USN-3901-2 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-46.49~16.04.1 | USN-3901-2 |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1009.11~16.04.1 | USN-3901-2 |
| Ubuntu 14.04 LTS | linux-azure | 4.15.0-1040.44~14.04.1 | USN-3901-2 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | kernel-alt | 4.14.0-115.7.1.el7a | RHSA-2019:0831 |
| RHEL 7 | perf +19 | 3.10.0-957.5.1.el7 | RHSA-2019:0831, RHSA-2019:0163 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7.5 EUS | perf +18 | 3.10.0-862.27.1.el7 | RHSA-2019:0202 |
| RHEL 7.4 EUS | perf +18 | 3.10.0-693.44.1.el7 | RHSA-2019:0324 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 | kernel-azure +2 | 4.12.14-5.19.1 | SUSE-SU-2019:0150-1 |
| SLES 15 | kernel-docs +6 | 4.12.14-25.28.1 | SUSE-SU-2019:0224-1 |
| SLES 12 SP4 | kernel-azure +2 | 4.12.14-6.6.2 | SUSE-SU-2019:0222-1 |
| SLES 12 SP4 | kernel-docs +4 | 4.12.14-95.6.1 | SUSE-SU-2019:0196-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP4 | kernel-azure +2 | 4.12.14-6.6.2 | SUSE-SU-2019:0222-1 |
| SLES for SAP 12 SP4 | kernel-syms +2 | 4.12.14-95.6.1 | SUSE-SU-2019:0196-1 |
| SLE Live Patching 15 | kernel-default | 4.12.14-25.28.1 | SUSE-SU-2019:0224-1 |
| SLE Live Patching 15 | kernel-livepatch-SLE15_Update_8 | 1-1.3.1 | SUSE-SU-2019:0224-1 |
| SLE Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_2 | 1-6.3.1 | SUSE-SU-2019:0196-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.0 | kernel-source | 4.12.14-lp150.12.45.1 | openSUSE-SU-2019:0065-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | kernel-uek +5 | 4.1.12-124.24.5.el7uek | ELSA-2019-4541, ELSA-2019-4528 |
| Oracle Linux 7 | kernel-uek-tools +3 | 4.14.35-1844.2.5.el7uek | ELSA-2019-4541 |
| Oracle Linux 7 | perf +12 | 3.10.0-957.5.1.el7 | ELSA-2019-4541, ELSA-2019-0163 |
Advisories 15
- RHSA-2019:0831 Red Hat Security Advisory: kernel-alt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:0324 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:0202 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:0163 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- USN-3901-1 linux, linux-aws, linux-gcp, linux-kvm, linux-oem, linux-oracle, linux-raspi2 vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- USN-3901-2 linux-hwe, linux-aws-hwe, linux-azure, linux-gcp, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- USN-3903-2 linux-hwe, linux-azure vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- SUSE-SU-2019:0222-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:0150-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:0224-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:0196-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:0065-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · May 2, 2025
- ELSA-2019-4541 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Feb 12, 2019
- ELSA-2019-4528 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jan 31, 2019
- ELSA-2019-0163 Important: kernel security, bug fix, and enhancement update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jan 29, 2019
References
- USN-3903-2 vendor-advisory
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.87
- https://github.com/torvalds/linux/commit/29ec90660d68bbdd69507c1c8b4e33aa299278b1
- USN-3901-2 vendor-advisory
- RHSA-2019:0324 vendor-advisory
- https://bugs.chromium.org/p/project-zero/issues/detail?id=1700
- RHSA-2019:0202 vendor-advisory
- RHSA-2019:0163 vendor-advisory
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=29ec90660d68bbdd69507c1c8b4e33aa299278b1
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.7
- USN-3901-1 vendor-advisory
- USN-3903-1 vendor-advisory
- RHSA-2019:0831 vendor-advisory
- RHBA-2019:0327 vendor-advisory