Vulnerability · Published Jan 5, 2024 · Assigned by XEN
CVE-2023-46836x86: BTC/SRSO fixes not fully effective
Medium 4.7
In plain English
A medium-severity security flaw in Xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-safe. It was believed that the mitigations always operated in contexts with IRQs disabled. However, the original XSA-254 fix for Meltdown (XPTI) deliberately left interrupts enabled on two entry paths; one unconditionally, and one conditionally on whether XPTI was active. As BTC/SRSO and Meltdown affect different CPU vendors, the mitigations are not active together by default. Therefore, there is a race condition whereby a malicious PV guest can bypass BTC/SRSO protections and launch a BTC/SRSO attack against Xen.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46836 |
| Alpine:v3.21 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46836 |
| Alpine:v3.22 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46836 |
| Alpine:v3.23 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46836 |
| Alpine:v3.24 | xen | 4.17.2-r4 | ALPINE-CVE-2023-46836 |
| Debian:12 | xen | 4.17.2+76-ge1f9cb16e2-1~deb12u1 | DEBIAN-CVE-2023-46836 |
| Debian:13 | xen | 4.17.2+76-ge1f9cb16e2-1 | DEBIAN-CVE-2023-46836 |
| Debian:14 | xen | 4.17.2+76-ge1f9cb16e2-1 | DEBIAN-CVE-2023-46836 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46836 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46836 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2023-46836 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2023-46836 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2023-46836 |