Vulnerability in Xen
CVE-2020-25601
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (34.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 34.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Xen
- Debian Linux — versions 10.0
- Fedoraproject Fedora — versions 31, 32, 33
- openSUSE Leap — versions 15.2
References
- xenbits.xen.org/xsa/advisory-344.html (Vendor Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- www.debian.org/security/2020/dsa-4769 (vendor-advisory, Third Party Advisory)
- lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html (vendor-advisory, Mailing List, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202011-06 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-25601?
- CVE-2020-25601 is a medium-severity vulnerability in Xen. CVSS score: 5.5/10. Published 2020-09-23.
- How severe is CVE-2020-25601?
- Medium severity. CVSS v3 base score is 5.5 out of 10.