Description
An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.
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 | 4.14.0+80-gd101b417b7-1 | — |
| Debian 13 | xen | 4.14.0+80-gd101b417b7-1 | — |
| Debian 12 | xen | 4.14.0+80-gd101b417b7-1 | — |
| Debian 10 | xen | 4.11.4+37-g3263f257ca-1 | DSA-4769-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | xen | 4.11.3+24-g14b62ab3e5-1ubuntu2.3 | USN-5617-1 |
| Ubuntu 18.04 LTS | xen | No fix yet | — |
| Ubuntu 16.04 LTS | xen | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | xen | 4.13.1_08-3.10.1 | SUSE-SU-2020:2791-1 |
| SLES 15 SP1 | xen | 4.12.3_08-3.28.1 | SUSE-SU-2020:2790-1 |
| SLES 12 SP5 | xen | 4.12.3_08-3.24.1 | SUSE-SU-2020:2788-1 |
| SLES 12 SP4 | xen | 4.11.4_08-2.36.1 | SUSE-SU-2020:2786-1 |
| SLES 12 SP3 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | xen | 4.7.6_10-43.67.1 | SUSE-SU-2020:2822-1 |
| SLES 11 SP4 | xen | 4.4.4_44-61.55.1 | SUSE-SU-2020:14521-1 |
| SLES for SAP 15 | xen | 4.10.4_16-3.41.1 | SUSE-SU-2020:2789-1 |
| SLES for SAP 12 SP5 | xen | 4.12.3_08-3.24.1 | SUSE-SU-2020:2788-1 |
| SLES for SAP 12 SP4 | xen | 4.11.4_08-2.36.1 | SUSE-SU-2020:2786-1 |
| SLES for SAP 12 SP3 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
| SLES for SAP 12 SP2 | xen | 4.7.6_10-43.67.1 | SUSE-SU-2020:2822-1 |
| SLE HPC 15 | xen | 4.10.4_16-3.41.1 | SUSE-SU-2020:2789-1 |
| SUSE OpenStack Cloud Crowbar 9 | xen | 4.11.4_08-2.36.1 | SUSE-SU-2020:2786-1 |
| SUSE OpenStack Cloud Crowbar 8 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
| SUSE OpenStack Cloud 9 | xen | 4.11.4_08-2.36.1 | SUSE-SU-2020:2786-1 |
| SUSE OpenStack Cloud 8 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
| SUSE OpenStack Cloud 7 | xen | 4.7.6_10-43.67.1 | SUSE-SU-2020:2822-1 |
| SUSE HPE Helion OpenStack 8 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
| SUSE Enterprise Storage 5 | xen | 4.9.4_12-3.74.1 | SUSE-SU-2020:2787-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | xen | 4.15.1_01-1.2 | openSUSE-SU-2024:11520-1 |
| openSUSE Leap 15.2 | xen | 4.13.1_08-lp152.2.9.1 | openSUSE-SU-2020:1608-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | xen | 4.14.0-r1 | — |
| Alpine v3.23 | xen | 4.14.0-r1 | — |
| Alpine v3.22 | xen | 4.14.0-r1 | — |
| Alpine v3.21 | xen | 4.14.0-r1 | — |
| Alpine v3.20 | xen | 4.14.0-r1 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | xen | 4.14.0-r1 | — |
| Alpine v3.18 | xen | 4.14.0-r1 | — |
| Alpine v3.17 | xen | 4.14.0-r1 | — |
| Alpine v3.16 | xen | 4.14.0-r1 | — |
| Alpine v3.15 | xen | 4.14.0-r1 | — |
| Alpine v3.14 | xen | 4.14.0-r1 | — |
| Alpine v3.13 | xen | 4.14.0-r1 | — |
| Alpine v3.12 | xen | 4.13.1-r4 | — |
| Alpine v3.11 | xen | 4.13.1-r4 | — |
| Alpine v3.10 | xen | 4.12.3-r4 | — |
| Alpine v3.9 | xen | 4.11.4-r2 | — |
Advisories 12
- USN-5617-1 xen vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-4769-1 xen - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2020:2791-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2787-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2786-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:14521-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1608-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2789-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2822-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2788-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11520-1 xen-4.15.1_01-1.2 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- SUSE-SU-2020:2790-1 Security update for xen SUSE / openSUSE Security Updates · May 2, 2025
References
- https://xenbits.xen.org/xsa/advisory-344.html
- FEDORA-2020-306b84fd07 vendor-advisory
- FEDORA-2020-f668e579be vendor-advisory
- DSA-4769 vendor-advisory
- openSUSE-SU-2020:1608 vendor-advisory
- FEDORA-2020-d46fe34349 vendor-advisory
- GLSA-202011-06 vendor-advisory