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Fencer Intel
high 8.6

CVE-2015-8555 json

Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and XMM registers when XSAVE/XRSTOR are not used to manage gues…

published 10y ago modified 4mo ago also EUVD-2015-8435

cvss
8.6
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and XMM registers when XSAVE/XRSTOR are not used to manage guest extended register state, which allows local guest domains to obtain sensitive information from other domains via unspecified vectors.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.8.0~rc3-1

debian advisories DEBIAN-CVE-2015-8555

  • xen Ubuntu 14.04 LTS 4.4.2-0ubuntu0.14.04.4

ubuntu advisories UBUNTU-CVE-2015-8555

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • xen SLES for SAP 12, SLES 12, SLED 12 +1 more 4.4.4_02-22.19.1
  • xen SLES for SAP 11 SP4, SLES 11 SP4, SLED 11 SP4 +1 more 4.4.4_02-32.1
  • xen SLES for SAP 12 SP1, SLES 12 SP1, SLED 12 SP1 +1 more 4.5.2_06-7.1
  • xen SLES 11 SP3-LTSS 4.2.5_20-24.9
  • xen SLES 11 SP2-LTSS 4.1.6_08-26.1

suse advisories SUSE-SU-2016:1745-1SUSE-SU-2016:1318-1SUSE-SU-2016:1154-1SUSE-SU-2016:0955-1SUSE-SU-2016:0873-1

  • xen openSUSE Tumbleweed 4.7.0_12-1.3

opensuse advisories openSUSE-SU-2024:10196-1

Is CVE-2015-8555 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2015-8555 updated cvss 1.8

xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)

  • Red Hat Enterprise Linux 5 xen
    affected: no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.25% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.6 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.