An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via a VCPUOP_initialise hypercall. hypercall_create_continuation() is a variadic function which uses a printf-like format string to interpret its parameters. Error handling for a bad format character was done using BUG(), which crashes Xen. One path, via the VCPUOP_initialise hypercall, has a bad format character. The BUG() can be hit if VCPUOP_initialise executes for a sufficiently long period of time for a continuation to be created. Malicious guests may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen versions 4.6 and newer are vulnerable. Xen versions 4.5 and earlier are not vulnerable. Only x86 PV guests can exploit the vulnerability. HVM and PVH guests, and guests on ARM systems, cannot exploit the vulnerability.
CVSS Details
- CVSS 3.1 Base Score: 6.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | Upgrade xen | Oct 1, 2024 | Oct 31, 2019 |
| Debian | — | Upgrade xen | Jan 16, 2020 | Oct 31, 2019 |
| Gentoo Linux | — | Upgrade app-emulation/xen-tools.Upgrade app-emulation/xen. | Mar 27, 2020 | Oct 31, 2019 |
| Suse | — | Upgrade xenUpgrade xen-toolsUpgrade xen-libs-32bitUpgrade xen-libsUpgrade xen-develUpgrade xen-kmp-defaultUpgrade xen-kmp-paeUpgrade xen-doc-htmlUpgrade xen-tools-domu | Nov 13, 2019 | Oct 31, 2019 |
| Ubuntu | — | No solution exists | Jun 26, 2025 | Oct 31, 2019 |
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