Description
The mbcache feature in the ext2 and ext4 filesystem implementations in the Linux kernel before 4.6 mishandles xattr block caching, which allows local users to cause a denial of service (soft lockup) via filesystem operations in environments that use many attributes, as demonstrated by Ceph and Samba.
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 | 4.6.1-1 | — |
| Debian 13 | linux | 4.6.1-1 | — |
| Debian 12 | linux | 4.6.1-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-gcp-6.11 +4 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +2 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +3 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1053.57 | — |
| Ubuntu 16.04 LTS | linux | 4.4.0-116.140 | USN-3582-1 |
| Ubuntu 16.04 LTS | linux-aws | 4.4.0-1052.61 | USN-3582-1 |
| Ubuntu 16.04 LTS | linux-kvm | 4.4.0-1019.24 | USN-3582-1 |
| Ubuntu 16.04 LTS | linux-raspi2 | 4.4.0-1085.93 | USN-3582-1 |
| Ubuntu 16.04 LTS | linux-snapdragon | 4.4.0-1087.92 | USN-3582-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | linux-aws | 4.4.0-1014.14 | USN-3582-2 |
| Ubuntu 14.04 LTS | linux-lts-xenial | 4.4.0-116.140~14.04.1 | USN-3582-2 |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | 4.4.0-1005.5 | — |
| Ubuntu Pro 20.04 LTS | linux-azure-fde-5.15 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | dtrace-modules-4.1.12-61.1.33.el6uek | 0.5.3-2.el6 | ELSA-2017-3533 |
| Oracle Linux 7 | dtrace-modules-4.1.12-61.1.33.el7uek | 0.5.3-2.el7 | ELSA-2017-3533 |
| Oracle Linux 7 | kernel-uek +5 | 4.1.12-61.1.33.el7uek | ELSA-2017-3533 |
Advisories 3
- USN-3582-1 linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- USN-3582-2 linux-lts-xenial, linux-aws vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- ELSA-2017-3533 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Mar 31, 2017
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1360968
- https://github.com/torvalds/linux/commit/f9a61eb4e2471c56a63cd804c7474128138c38ac
- https://github.com/torvalds/linux/commit/82939d7999dfc1f1998c4b1c12e2f19edbdff272
- USN-3582-1 vendor-advisory
- https://bugzilla.kernel.org/show_bug.cgi?id=107301
- [oss-security] 20160825 Re: CVE request: Linux kernel mbcache lock contention denial of service. mailing-list
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=82939d7999dfc1f1998c4b1c12e2f19edbdff272
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=be0726d33cb8f411945884664924bed3cb8c70ee
- [oss-security] 20160822 CVE request: Linux kernel mbcache lock contention denial of service. mailing-list
- https://github.com/torvalds/linux/commit/be0726d33cb8f411945884664924bed3cb8c70ee
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f9a61eb4e2471c56a63cd804c7474128138c38ac
- https://lwn.net/Articles/668718/
- USN-3582-2 vendor-advisory