CVE-2015-8555
published 2016-04-13CVE-2015-8555: 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…
PriorityP341high8.6CVSS 3.0
AVNACLPRNUINSCCHINAN
EPSS
2.25%
81.0th percentile
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.
Affected
29 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| citrix | citrix_adm | — | — |
| citrix | citrix_hypervisor | — | — |
| citrix | citrix_virtual_apps_and_desktops | — | — |
| citrix | endpoint_management | — | — |
| citrix | netscaler_adc | — | — |
| citrix | netscaler_gateway | — | — |
| citrix | xenserver | — | — |
| citrix | xenserver | — | — |
| debian | xen | < xen 4.8.0~rc3-1 (bookworm) | xen 4.8.0~rc3-1 (bookworm) |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
| xen | xen | — | — |
CVSS provenance
nvdv3.08.6HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:P/I:N/A:N
osv8.6HIGH
vendor_debian8.6HIGH
vendor_redhat8.6HIGH
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
Red Hat
xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
vendor_redhat·2015-12-17·CVSS 8.6
CVE-2015-8555 [HIGH] xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
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.
Package: xen (Red Hat Enterprise Linux 5) - Will not fix
Debian
CVE-2015-8555: xen - Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and ...
vendor_debian·2015·CVSS 8.6
CVE-2015-8555 [HIGH] CVE-2015-8555: xen - Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and ...
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.
Scope: local
bookworm: resolved (fixed in 4.8.0~rc3-1)
bullseye: resolved (fixed in 4.8.0~rc3-1)
forky: resolved (fixed in 4.8.0~rc3-1)
sid: resolved (fixed in 4.8.0~rc3-1)
trixie: resolved (fixed in 4.8.0~rc3-1)
Citrix
Citrix Security Bulletin CTX203879
vendor_citrix·CVSS 8.6
CVE-2015-8555 [HIGH] Citrix Security Bulletin CTX203879
Citrix Security Bulletin CTX203879
CVE References: CVE-2015-8555, CVE-2025-12101, CVE-2025-62626, CVE-2026-23554, CVE-2026-3055, CVE-2026-4368, CVE-2026-4397
Affected Products: Citrix ADM, Citrix Hypervisor, Citrix Virtual Apps and Desktops, Endpoint Management, NetScaler ADC, NetScaler Gateway, XenServer
GHSA
GHSA-ffhp-28g8-p5m9: Xen 4
ghsa_unreviewed·2022-05-17
CVE-2015-8555 [HIGH] CWE-200 GHSA-ffhp-28g8-p5m9: Xen 4
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.
OSV
CVE-2015-8555: Xen 4
osv·2016-04-13·CVSS 8.6
CVE-2015-8555 [HIGH] CVE-2015-8555: Xen 4
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.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2015-8554 CVE-2015-8555 CVE-2015-8550 CVE-2015-8551 CVE-2015-8552 CVE-2015-2150 CVE-2015-8553 xen: various flaws [fedora-all]
bugzilla·2015-12-17·CVSS 4.9
CVE-2015-8554 [MEDIUM] CVE-2015-8554 CVE-2015-8555 CVE-2015-8550 CVE-2015-8551 CVE-2015-8552 CVE-2015-2150 CVE-2015-8553 xen: various flaws [fedora-all]
CVE-2015-8554 CVE-2015-8555 CVE-2015-8550 CVE-2015-8551 CVE-2015-8552 CVE-2015-2150 CVE-2015-8553 xen: various flaws [fedora-all]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of Fedora.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
NOTE
Bugzilla
CVE-2015-8555 xsa165 xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
bugzilla·2015-12-07·CVSS 8.6
CVE-2015-8555 [HIGH] CVE-2015-8555 xsa165 xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
CVE-2015-8555 xsa165 xen: information leak in legacy x86 FPU/XMM initialization (XSA-165)
ISSUE DESCRIPTION
When XSAVE/XRSTOR are not in use by Xen to manage guest extended
register state, the initial values in the FPU stack and XMM registers
seen by the guest upon first use are those left there by the previous
user of those registers.
IMPACT
A malicious domain may be able to leverage this to obtain sensitive
information such as cryptographic keys from another domain.
VULNERABLE SYSTEMS
All Xen versions are vulnerable.
Only x86 systems without XSAVE support or with XSAVE support disabled
are vulnerable.
ARM systems are not vulnerable.
MITIGATION
On XSAVE capable systems, not turning off XSAVE support via the
"no-xsave" hypervisor command line option (or - when defaulting to
off -
http://support.citrix.com/article/CTX203879http://www.debian.org/security/2016/dsa-3519http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.htmlhttp://www.securityfocus.com/bid/79543http://www.securitytracker.com/id/1034477http://xenbits.xen.org/xsa/advisory-165.htmlhttps://security.gentoo.org/glsa/201604-03http://support.citrix.com/article/CTX203879http://www.debian.org/security/2016/dsa-3519http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.htmlhttp://www.securityfocus.com/bid/79543http://www.securitytracker.com/id/1034477http://xenbits.xen.org/xsa/advisory-165.htmlhttps://security.gentoo.org/glsa/201604-03
2016-04-13
Published