CVE-2023-46836
Last modified
CVE-2023-46836 is a medium-severity vulnerability rated 4.7/10 on the CVSS scale. 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. EPSS estimates a 0.25% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Xen | Xen | All versions |
References
- https://xenbits.xenproject.org/xsa/advisory-446.htmlPatch, Vendor Advisory
- https://xenbits.xenproject.org/xsa/advisory-446.htmlPatch, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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