Vulnerability Details : CVE-2020-25597
An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit max_event_channels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting max_event_channels, are not vulnerable.
Vulnerability category: Denial of service
Products affected by CVE-2020-25597
- cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2020-25597
0.05%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 12 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2020-25597
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
6.1
|
MEDIUM | AV:L/AC:L/Au:N/C:P/I:P/A:C |
3.9
|
8.5
|
NIST | |
6.5
|
MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |
2.0
|
4.0
|
NIST |
CWE ids for CVE-2020-25597
-
The product does not handle or incorrectly handles an exceptional condition.Assigned by: nvd@nist.gov (Primary)
References for CVE-2020-25597
-
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html
[security-announce] openSUSE-SU-2020:1608-1: important: Security updateMailing List;Third Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE/
[SECURITY] Fedora 31 Update: xen-4.12.3-5.fc31 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
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https://xenbits.xen.org/xsa/advisory-338.html
XSA-338 - Xen Security AdvisoriesPatch;Vendor Advisory
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https://security.gentoo.org/glsa/202011-06
Xen: Multiple vulnerabilities (GLSA 202011-06) — Gentoo securityThird Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/
[SECURITY] Fedora 33 Update: xen-4.14.0-5.fc33 - package-announce - Fedora Mailing-ListsThird Party Advisory
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https://www.debian.org/security/2020/dsa-4769
Debian -- Security Information -- DSA-4769-1 xenThird Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM/
[SECURITY] Fedora 32 Update: xen-4.13.1-6.fc32 - package-announce - Fedora Mailing-ListsThird Party Advisory
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