Description
The pygrub boot loader emulator in Xen, when nul-delimited output format is requested, allows local pygrub-using guest OS administrators to read or delete arbitrary files on the host via NUL bytes in the bootloader configuration file.
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 | xen | 4.8.0-1 | — |
| Debian 13 | xen | 4.8.0-1 | — |
| Debian 12 | xen | 4.8.0-1 | — |
| Debian 8 | xen | 4.4.1-9+deb8u8 | DSA-3729-1 |
| Debian 7 | xen | 4.1.6.lts1-4 | DLA-720-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | xen | 4.6.0-1ubuntu4.3 | — |
| Ubuntu 14.04 LTS | xen | 4.4.2-0ubuntu0.14.04.9 | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | xen | 4.7.1_02-25.1 | SUSE-SU-2016:3067-1 |
| SLES 12 SP1 | xen | 4.5.5_02-22.3.1 | SUSE-SU-2016:3083-1 |
| SLES 12 | xen | 4.4.4_05-22.25.1 | SUSE-SU-2016:3156-1 |
| SLES 11 SP4 | xen | 4.4.4_10-43.5 | SUSE-SU-2016:3174-1 |
| SLES 11 SP3 | xen | 4.2.5_21-30.1 | SUSE-SU-2016:3273-1 |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 11 SP2 | xen | 4.1.6_08-32.1 | SUSE-SU-2016:3044-1 |
| SLES for SAP 12 SP2 | xen | 4.7.1_02-25.1 | SUSE-SU-2016:3067-1 |
| SLES for SAP 12 SP1 | xen | 4.5.5_02-22.3.1 | SUSE-SU-2016:3083-1 |
| SLES for SAP 12 | xen | 4.4.4_05-22.25.1 | SUSE-SU-2016:3156-1 |
| SLES for SAP 11 SP4 | xen | 4.4.4_10-43.5 | SUSE-SU-2016:3174-1 |
| SUSE OpenStack Cloud 5 | xen | 4.2.5_21-30.1 | SUSE-SU-2016:3273-1 |
| SUSE Manager Proxy 2.1 | xen | 4.2.5_21-30.1 | SUSE-SU-2016:3273-1 |
| SUSE Manager 2.1 | xen | 4.2.5_21-30.1 | SUSE-SU-2016:3273-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | xen | 4.2.5_21-30.1 | SUSE-SU-2016:3273-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | xen | 4.7.1-r1 | — |
| Alpine v3.23 | xen | 4.7.1-r1 | — |
| Alpine v3.22 | xen | 4.7.1-r1 | — |
| Alpine v3.21 | xen | 4.7.1-r1 | — |
| Alpine v3.20 | xen | 4.7.1-r1 | — |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | xen | 4.7.1-r1 | — |
| Alpine v3.18 | xen | 4.7.1-r1 | — |
| Alpine v3.17 | xen | 4.7.1-r1 | — |
| Alpine v3.16 | xen | 4.7.1-r1 | — |
| Alpine v3.15 | xen | 4.7.1-r1 | — |
| Alpine v3.14 | xen | 4.7.1-r1 | — |
| Alpine v3.13 | xen | 4.7.1-r1 | — |
| Alpine v3.12 | xen | 4.7.1-r1 | — |
| Alpine v3.11 | xen | 4.7.1-r1 | — |
| Alpine v3.10 | xen | 4.7.1-r1 | — |
| Alpine v3.9 | xen | 4.7.1-r1 | — |
| Alpine v3.8 | xen | 4.7.1-r1 | — |
| Alpine v3.7 | xen | 4.7.1-r1 | — |
| Alpine v3.6 | xen | 4.7.1-r1 | — |
| Alpine v3.5 | xen | 4.7.1-r1 | — |
Advisories 8
- DLA-720-1 xen - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3729-1 xen - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2016:3044-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3067-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3174-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3156-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3273-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3083-1 Security update for xen SUSE / openSUSE Security Updates · May 2, 2025
References
- http://xenbits.xen.org/xsa/xsa198.patch
- 94473 vdb-entry
- GLSA-201612-56 vendor-advisory
- http://xenbits.xen.org/xsa/advisory-198.html
- 1037347 vdb-entry
- https://support.citrix.com/article/CTX218775