CVE-2020-15565: debian debian_linux Uncontrolled Resource Consumption
Vulnerability summary
CVE-2020-15565 is a high (CVSS 8.8) Uncontrolled Resource Consumption vulnerability in debian debian_linux. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 30.2% of scored vulnerabilities.
Not severe (CVSS 8.8, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 13 · Related 12Timeline
- 07-07-2020PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames returned to Xen's free pool, and later reused for another purpose. Host crashes (leading to a Denial of Service) and privilege escalation cannot be ruled out. Xen versions from at least 3.2 onwards are affected. Only x86 Intel systems are affected. x86 AMD as well as Arm systems are not affected. Only x86 HVM guests using hardware assisted paging (HAP), having a passed through PCI device assigned, and having page table sharing enabled can leverage the vulnerability. Note that page table sharing will be enabled (by default) only if Xen considers IOMMU and CPU large page size support compatible.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated8.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated8.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS trend
Probability
0.36%
Chance of exploitation in the next 30 days
Percentile
30%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.37% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian2 products
- xen< 4.11.4+24-gddaaccbbab-1
- debian_linuxEOL10.0
Alpine1 product
- xen≥ 3.2.0, < 4.12.3-r2 | ≥ 3.2.0, < 4.13.1-r2 | ≥ 3.2.0, < 4.13.1-r4 | ≥ 3.2.0, < 4.11.4-r0
Fedoraproject1 product
- fedoraEOL31 | 32
Opensuse1 product
- leapEOL15.1 | 15.2
Ubuntu1 product
- xenAll versions (No fix recorded) | < 4.11.3+24-g14b62ab3e5-1ubuntu2.3
Xen1 product
- xen≥ 3.2.0, ≤ 4.13.1
6 vendors · 7 products
References
14 links- www.openwall.com/lists/oss-security/2020/07/07/4Mailing ListX Refsource MLISTREPORTThird Party Advisory
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00024.htmlVendor AdvisoryX Refsource SUSEMailing ListThird Party Advisory
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00031.htmlVendor AdvisoryX Refsource SUSEMailing ListThird Party Advisory