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.
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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
EUVD |
EUVD-2023-51002 | 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. |
Fixes
Solution
No solution given by the vendor.
Workaround
Running only HVM or PVH VMs will avoid the vulnerability.
References
History
Tue, 04 Nov 2025 20:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Tue, 03 Jun 2025 15:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Status: PUBLISHED
Assigner: XEN
Published:
Updated: 2025-11-04T19:25:42.692Z
Reserved: 2023-10-27T07:55:35.332Z
Link: CVE-2023-46836
Updated: 2025-11-04T19:25:42.692Z
Status : Modified
Published: 2024-01-05T17:15:11.197
Modified: 2025-11-04T20:17:10.557
Link: CVE-2023-46836
No data.
OpenCVE Enrichment
No data.
EUVD