high
7.8
CWE
269
Advisory Published
Updated

CVE-2020-25595

First published: Wed Sep 23 2020(Updated: )

An issue was discovered in Xen through 4.14.x. The PCI passthrough code improperly uses register data. Code paths in Xen's MSI handling have been identified that act on unsanitized values read back from device hardware registers. While devices strictly compliant with PCI specifications shouldn't be able to affect these registers, experience shows that it's very common for devices to have out-of-spec "backdoor" operations that can affect the result of these reads. A not fully trusted guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. Privilege escalation and information leaks cannot be excluded. All versions of Xen supporting PCI passthrough are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with passed through PCI devices may be able to leverage the vulnerability. Only systems passing through devices with out-of-spec ("backdoor") functionality can cause issues. Experience shows that such out-of-spec functionality is common; unless you have reason to believe that your device does not have such functionality, it's better to assume that it does.

Credit: cve@mitre.org cve@mitre.org

Affected SoftwareAffected VersionHow to fix
Xen Xen<=4.14.0
Fedoraproject Fedora=31
Fedoraproject Fedora=32
Fedoraproject Fedora=33
Debian Debian Linux=10.0
openSUSE Leap=15.2
debian/xen
4.14.6-1
4.14.5+94-ge49571868d-1
4.17.3+10-g091466ba55-1~deb12u1
4.17.3+36-g54dacb5c02-1

Remedy

https://xenbits.xen.org/xsa/advisory-337.html

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Reference Links

Frequently Asked Questions

  • What is CVE-2020-25595?

    CVE-2020-25595 is a vulnerability discovered in Xen through 4.14.x that involves the improper use of register data in the PCI passthrough code.

  • How does CVE-2020-25595 affect Xen?

    CVE-2020-25595 affects Xen versions up to 4.14.x.

  • What can happen if my system is affected by CVE-2020-25595?

    If your system is affected by CVE-2020-25595, code paths in Xen's MSI handling may act on unsanitized values read back from device hardware registers, potentially leading to security vulnerabilities.

  • How can I fix CVE-2020-25595?

    To fix CVE-2020-25595, you should update your Xen software to version 4.11.3+24 or apply the appropriate remediation provided by your operating system vendor.

  • Where can I find more information about CVE-2020-25595?

    You can find more information about CVE-2020-25595 on the Xen project's advisory page (https://xenbits.xen.org/xsa/advisory-337.html).

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