CVE-2020-25601
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 4.14.0+80-gd101b417b7-1 |
| sid | Fixed | 4.14.0+80-gd101b417b7-1 |
| forky | Fixed | 4.14.0+80-gd101b417b7-1 |
| bullseye | Fixed | 4.14.0+80-gd101b417b7-1 |
| bookworm | Fixed | 4.14.0+80-gd101b417b7-1 |
References
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.