CVE-2020-15567

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Summary

CVECVE-2020-15567
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2020-07-07 13:15:00 UTC
Updated2023-11-07 03:17:00 UTC
DescriptionAn issue was discovered in Xen through 4.13.x, allowing Intel guest OS users to gain privileges or cause a denial of service because of non-atomic modification of a live EPT PTE. When mapping guest EPT (nested paging) tables, Xen would in some circumstances use a series of non-atomic bitfield writes. Depending on the compiler version and optimisation flags, Xen might expose a dangerous partially written PTE to the hardware, which an attacker might be able to race to exploit. A guest administrator or perhaps even an unprivileged guest user might be able to cause denial of service, data corruption, or privilege escalation. Only systems using Intel CPUs are vulnerable. Systems using AMD CPUs, and Arm systems, are not vulnerable. Only systems using nested paging (hap, aka nested paging, aka in this case Intel EPT) are vulnerable. Only HVM and PVH guests can exploit the vulnerability. The presence and scope of the vulnerability depends on the precise optimisations performed by the compiler used to build Xen. If the compiler generates (a) a single 64-bit write, or (b) a series of read-modify-write operations in the same order as the source code, the hypervisor is not vulnerable. For example, in one test build using GCC 8.3 with normal settings, the compiler generated multiple (unlocked) read-modify-write operations in source-code order, which did not constitute a vulnerability. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code-generation options). The source code clearly violates the C rules, and thus should be considered vulnerable.

Risk And Classification

Problem Types: CWE-362

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Debian Debian Linux 10.0 All All All
Operating System Debian Debian Linux 10.0 All All All
Operating System Fedoraproject Fedora 31 All All All
Operating System Fedoraproject Fedora 32 All All All
Operating System Opensuse Leap 15.1 All All All
Operating System Opensuse Leap 15.2 All All All
Operating System Xen Xen All All All All

References

ReferenceSourceLinkTags
oss-security - Xen Security Advisory 328 v3 (CVE-2020-15567) - non-atomic modification of live EPT PTE MLIST www.openwall.com Mailing List, Third Party Advisory
Xen: Multiple vulnerabilities (GLSA 202007-02) — Gentoo security GENTOO security.gentoo.org
[SECURITY] Fedora 31 Update: xen-4.12.3-3.fc31 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[SECURITY] Fedora 32 Update: xen-4.13.1-4.fc32 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[security-announce] openSUSE-SU-2020:0985-1: important: Security update SUSE lists.opensuse.org
[SECURITY] Fedora 32 Update: xen-4.13.1-4.fc32 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org
[SECURITY] Fedora 31 Update: xen-4.12.3-3.fc31 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org
[security-announce] openSUSE-SU-2020:0965-1: important: Security update SUSE lists.opensuse.org
Debian -- Security Information -- DSA-4723-1 xen DEBIAN www.debian.org Third Party Advisory
XSA-328 - Xen Security Advisories MISC xenbits.xen.org Mitigation, Patch, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 198943 Ubuntu Security Notification for Xen Vulnerabilities (USN-5617-1)
  • 500790 Alpine Linux Security Update for xen
  • 501510 Alpine Linux Security Update for xen
  • 504534 Alpine Linux Security Update for xen
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