CVE-2023-46836
x86: BTC/SRSO fixes not fully effective
- State
- Published
- Severity
- 4.7 Medium
- Published
- Jan 5, 2024
- Updated
- Nov 4, 2025
- Reserved
- Oct 27, 2023
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 4.7 Medium | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N | CISA-ADP |
Weaknesses
The record names no weakness.
Affected Products
| Product | Versions |
|---|---|
XenXen |
|
References
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