Resource exhaustion in Xen
CVE-2020-29567
An issue was discovered in Xen 4.14.x. When moving IRQs between CPUs to distribute the load of IRQ handling, IRQ vectors are dynamically allocated and de-allocated on the relevant CPUs. De-allocation has to happen when certain constraints are met. If these conditions are not met when first checked, the checking CPU may send an interrupt to itself, in the expectation that this IRQ will be delivered only after the condition preventing the cleanup has cleared. For two specific IRQ vectors, this expectation was violated, resulting in a continuous stream of self-interrupts, which renders the CPU effectively unusable. A domain with a passed through PCI device can cause lockup of a physical CPU, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with physical PCI devices passed through to them can exploit the vulnerability.
EPSS: 0.004 (28.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Xen
- Fedoraproject Fedora — versions 33
- N/a — versions n/a
Weakness classification (CWE)
References
- cve@mitre.org (Patch, x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (x_refsource_FEDORA, vendor-advisory)
- cve@mitre.org (vendor-advisory, Third Party Advisory, x_refsource_GENTOO)
Frequently asked questions
- What is CVE-2020-29567?
- CVE-2020-29567 is a medium-severity vulnerability in Xen, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.2/10. Published 2020-12-15.
- How severe is CVE-2020-29567?
- Medium severity. CVSS v3 base score is 6.2 out of 10.