Description
The aufs module for the Linux kernel 3.x and 4.x does not properly restrict the mount namespace, which allows local users to gain privileges by mounting an aufs filesystem on top of a FUSE filesystem, and then executing a crafted setuid program.
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 | 3.18-1~exp1 | — |
| Debian 13 | linux | 3.18-1~exp1 | — |
| Debian 12 | linux | 3.18-1~exp1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu Nvidia-BlueField 22.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu 26.10 | linux-realtime +1 | No fix yet | — |
| Ubuntu 26.04 LTS | linux-gke +6 | No fix yet | — |
| Ubuntu 25.10 | linux-realtime +1 | No fix yet | — |
Show 19 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-gke +11 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-gke +11 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke-5.15 +2 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gke-4.15 +1 | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime +3 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime +2 | No fix yet | — |
| Ubuntu Pro FIPS 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux-ibm-5.15 +1 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | linux-gcp-4.15 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | linux | 4.4.0-222.255 | USN-5343-1 |
| Ubuntu Pro 16.04 LTS | linux-aws | 4.4.0-1138.152 | USN-5343-1 |
| Ubuntu Pro 16.04 LTS | linux-gcp | No fix yet | — |
| Ubuntu Pro 16.04 LTS | linux-kvm | 4.4.0-1103.112 | USN-5343-1 |
| Ubuntu Pro 14.04 LTS | linux | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux-aws | 4.4.0-1102.107 | USN-5343-1 |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-222.255~14.04.1 | USN-5343-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- AUFS (Ubuntu 15.10) - 'allow_userns' Fuse/Xattr User Namespaces Privilege Escalation EDB-41761 · local · Feb 19, 2016
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- USN-5343-1 linux, linux-aws, linux-kvm, linux-lts-xenial vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
References
- 96839 vdb-entry
- http://www.halfdog.net/Security/2016/AufsPrivilegeEscalationInUserNamespaces/
- [oss-security] 20160224 Aufs Union Filesystem Privilege Escalation In User Namespaces mailing-list
- [aufs] 20160219 aufs3 and aufs4 GIT release mailing-list
- [oss-security] 20211018 Re: CVE-2021-3847: OverlayFS - Potential Privilege Escalation using overlays copy_up mailing-list