Description
The outs instruction emulation in Xen 3.1.x, 4.2.x, 4.3.x, and earlier, when using FS: or GS: segment override, uses an uninitialized variable as a segment base, which allows local 64-bit PV guests to obtain sensitive information (hypervisor stack content) via unspecified vectors related to stale data in a segment register.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | xen | 4.4.0-1 | — |
| Debian 13 | xen | 4.4.0-1 | — |
| Debian 12 | xen | 4.4.0-1 | — |
| Debian 7 | xen | 4.1.4-3+deb7u2 | DSA-3006-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | kernel +12 | 2.6.18-371.1.2.el5 | RHSA-2013:1449 |
Advisories 2
- RHSA-2013:1449 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- DSA-3006-1 xen - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- SUSE-SU-2014:0470 vendor-advisory
- GLSA-201407-03 vendor-advisory
- [oss-security] 20131010 Xen Security Advisory 67 (CVE-2013-4368) - Information leak through outs instruction emulation mailing-list
- xen-cve20134368-info-disc(87799) vdb-entry
- RHSA-2013:1449 vendor-advisory
- SUSE-SU-2014:0446 vendor-advisory
- DSA-3006 vendor-advisory
- SUSE-SU-2014:0411 vendor-advisory
- openSUSE-SU-2013:1636 vendor-advisory