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CVE-2016-9379

The pygrub boot loader emulator in Xen, when S-expression output format is requested, allows local pygrub-using guest OS administrators to read or delete arbitrary files on the host via string quotes and S-expressions in the bootloader configuration file.

Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.9, requiring local system access to exploit with relatively low complexity without requiring user interaction . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 2 products from xen, from citrix organizations running these solutions should prioritize assessment and patching.

Historical Context

First disclosed in 2017, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.

Published

2017-01-23T21:59:02.707

Last Modified

2025-04-20T01:37:25.860

Status

Deferred

Source

[email protected]

Severity

CVSSv3.0: 7.9 (HIGH)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:P/I:P/A:P

Access Vector: LOCAL
Access Complexity: LOW
Authentication: NONE
Confidentiality Impact: PARTIAL
Integrity Impact: PARTIAL
Availability Impact: PARTIAL

Exploitability Score

3.9

Impact Score

6.4

Weaknesses

Type: Primary
CWE-20

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Operating System	xen	xen	*	Yes
Application	citrix	xenserver	6.0.2	Yes
Application	citrix	xenserver	6.2.0	Yes
Application	citrix	xenserver	6.5	Yes
Application	citrix	xenserver	7.0	Yes

References

http://www.securityfocus.com/bid/94473 Third Party Advisory, VDB Entry ([email protected])
http://www.securitytracker.com/id/1037347 Third Party Advisory, VDB Entry ([email protected])
http://xenbits.xen.org/xsa/advisory-198.html Patch, Vendor Advisory ([email protected])
http://xenbits.xen.org/xsa/xsa198.patch Patch, Vendor Advisory ([email protected])
https://security.gentoo.org/glsa/201612-56 ([email protected])
https://support.citrix.com/article/CTX218775 Patch, Third Party Advisory ([email protected])
http://www.securityfocus.com/bid/94473 Third Party Advisory, VDB Entry (af854a3a-2127-422b-91ae-364da2661108)
http://www.securitytracker.com/id/1037347 Third Party Advisory, VDB Entry (af854a3a-2127-422b-91ae-364da2661108)
http://xenbits.xen.org/xsa/advisory-198.html Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://xenbits.xen.org/xsa/xsa198.patch Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://security.gentoo.org/glsa/201612-56 (af854a3a-2127-422b-91ae-364da2661108)
https://support.citrix.com/article/CTX218775 Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For xen's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.