CVE-2023-46836
CVE-2023-46836 is a medium-severity vulnerability in Xen with a CVSS 3.x base score of 4.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Medium (CVSS 3.x base score 4.7)
- EPSS exploit prediction: 0% (16th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2023-51002
- Affected product: Xen
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2023-46836?
- 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.
- How severe is CVE-2023-46836?
- CVE-2023-46836 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
- Is CVE-2023-46836 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2023-46836?
- CVE-2023-46836 affects Xen. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2023-46836?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2023-46836 have an EU (EUVD) identifier?
- Yes. CVE-2023-46836 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-51002.
- When was CVE-2023-46836 published?
- CVE-2023-46836 was published on 2024-01-05 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
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