Quick answers
- Is CVE-2016-10013 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2016-10013 being exploited in the wild.
- How severe is CVE-2016-10013?
- High severity, with a CVSS score of 7.8, published 26 January 2017.
- Which products and versions are affected?
- Xen Project Xen through 4.8.x.
- Is there a fix for CVE-2016-10013?
- A patch was published on 2017-05-09: Debian security update released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2016-10013 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2016-10013?
- Check whether you run Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A privilege escalation vulnerability exists in the Xen x86 instruction emulator's handling of the SYSCALL instruction. The emulator incorrectly raises singlestep (#DB) exceptions based on processor flags present at the start of the instruction rather than the end, deviating from expected hardware behavior for SYSCALL. An unprivileged user in a 64-bit x86 HVM guest can exploit this logic error to trigger an unexpected exception frame, potentially leading to kernel-level privilege escalation within the guest. The vulnerability is most prominent in Xen 4.6 and earlier; in version 4.7 and later, it typically requires specific non-default CPUID configurations or existing hardware access privileges. Linux guests are generally mitigated if they use an Interrupt Stack Table (IST) for #DB handling. Patches are available for supported Xen versions (XSA-204).
Affected products
- Xen Project Xen through 4.8.x
Timeline
- 2016-12-19: advisory: XSA-204 released by Xen Project
- 2017-01-26: disclosed: NVD publication date
- 2017-05-09: patched: Debian security update released