Description
The Linux kernel through 3.17.4 does not properly restrict dropping of supplemental group memberships in certain namespace scenarios, which allows local users to bypass intended file permissions by leveraging a POSIX ACL containing an entry for the group category that is more restrictive than the entry for the other category, aka a "negative groups" issue, related to kernel/groups.c, kernel/uid16.c, and kernel/user_namespace.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 | 3.16.7-ckt4-1 | — |
| Debian 13 | linux | 3.16.7-ckt4-1 | — |
| Debian 12 | linux | 3.16.7-ckt4-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-riscv +6 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +2 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +4 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +3 | No fix yet | — |
| Ubuntu 14.04 LTS | linux | 3.13.0-46.75 | USN-2516-1 |
| Ubuntu 14.04 LTS | linux-lts-utopic | 3.16.0-31.41~14.04.1 | USN-2517-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | linux-azure-fde-5.15 | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | dtrace-modules-3.8.13-98.el6uek | 0.4.5-2.el6 | ELSA-2015-3064 |
| Oracle Linux 7 | dtrace-modules-shared-headers +2 | 0.4.5-3.el7 | ELSA-2015-3064 |
| Oracle Linux 7 | kernel-uek +5 | 3.8.13-98.el7uek | ELSA-2015-3064 |
Advisories 3
- USN-2516-1 linux vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- USN-2517-1 linux-lts-utopic vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- ELSA-2015-3064 Important: Unbreakable Enterprise kernel security , bug fix and enhancement update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jul 30, 2015
References
- FEDORA-2015-0517 vendor-advisory
- USN-2515-1 vendor-advisory
- 71154 vdb-entry
- USN-2518-1 vendor-advisory
- MDVSA-2015:058 vendor-advisory
- FEDORA-2015-0515 vendor-advisory
- http://thread.gmane.org/gmane.linux.man/7385/
- USN-2517-1 vendor-advisory
- [oss-security] 20141120 Re: Linux user namespaces can bypass group-based restrictions - Linux kernel mailing-list
- USN-2516-1 vendor-advisory