CVE-2019-19581: An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain b...

Description

An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

EPSS Probability

0.37%

29.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-119

Affected Software

Vendor	Product	Versions
Xen	Xen	>= 4.8.0, <= 4.12.1
Fedoraproject	Fedora	31

References

Timeline

Published: Dec 11, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-19581?

An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.

How severe is CVE-2019-19581?

CVE-2019-19581 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2019-19581?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.