- Description
- In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the previous vCPU to run. While safe for Xen's isolation between vCPUs, this prevents the guest kernel correctly isolating between tasks. Consider: 1) vCPU runs on CPU A, running task 1. 2) vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB. 3) On CPU B, guest kernel switches from task 1 to 2, issuing IBPB. 4) vCPU moves back to CPU A. Xen skips IBPB again. Now, task 2 is running on CPU A with task 1's training still in the BTB.
- Source
- security@xen.org
- NVD status
- Analyzed
- Products
- xen
CVSS 3.1
- Type
- Secondary
- Base score
- 2.9
- Impact score
- 1.4
- Exploitability score
- 1.4
- Vector string
- CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- Severity
- LOW
- 134c704f-9b21-4f2e-91b3-4a467353bcc0
- CWE-665
- Hype score
- Not currently trending
🚨 Attention System Administrators & DevOps Teams! 🚨 Mageia has released a critical security update, MGASA-2026-0026, patching two high-severity Xen hypervisor vulnerabilities (CVE-2025-58150 & CVE-2026-23553). Read more: 👉 https://t.co/yZg1dIbOrU #Security https
@Cezar_H_Linux
30 Jan 2026
55 Impressions
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URGENT: #openSUSE Leap 15.6 users must patch Xen hypervisor vulnerabilities CVE-2025-58150 (buffer overrun) and CVE-2026-23553 (incomplete IBPB). Read more: 👉 https://t.co/vGoK29zDFU #Security https://t.co/IgMwGkuP5z
@Cezar_H_Linux
28 Jan 2026
36 Impressions
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3 new Xen Security Advisories https://t.co/O4qDUqCDdd 477 CVE-2025-58150 x86: buffer overrun with shadow paging + tracing 478 CVE-2025-58151 varstored: TOCTOU issues with mapped guest memory 479 CVE-2026-23553 x86: incomplete IBPB for vCPU isolation
@oss_security
28 Jan 2026
558 Impressions
1 Retweet
7 Likes
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CVE-2026-23553 x86: incomplete IBPB for vCPU isolation CVE-2025-58151 varstored: TOCTOU issues with mapped guest memory CVE-2025-58150 x86: buffer overrun with shadow paging + tracing Xen Security Advisories https://t.co/aGhjl6MOAL
@autumn_good_35
27 Jan 2026
296 Impressions
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