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CVE-2026-93834— Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape

Quick assessment

Affected
Red Hat Red Hat Enterprise Linux 10
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 QEMU 的 9pfs 子系统中发现了一个 use-after-free（释放后使用）漏洞。主线程与工作线程在处理并发的 Tlcreate 和 Twalk 请求时存在竞争条件，恶意访客用户可构造包含堆中过期数据的 fid 路径，从而绕过目录遍历限制，突破共享目录边界。这可能导致以 QEMU 进程用户身份进行任意主机文件读写及代码执行（虚拟机逃逸）。

CVSS 8.8 · High EPSS 0.38% · P29
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I. Basic Information for CVE-2026-93834

Vulnerability Information
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Vulnerability Title
Qemu-kvm: 9pfs: use-after-free race in tlcreate/twalk allows vm guest escape
Source: CVE Program / CVE List V5
Vulnerability Description
A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution (VM escape) as the QEMU process user.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat Enterprise Linux 10 - cpe:/o:redhat:enterprise_linux:10
Red Hat Red Hat Enterprise Linux 6 - cpe:/o:redhat:enterprise_linux:6
Red Hat Red Hat Enterprise Linux 7 - cpe:/o:redhat:enterprise_linux:7
Red Hat Red Hat Enterprise Linux 7 - cpe:/o:redhat:enterprise_linux:7
Red Hat Red Hat Enterprise Linux 8 - cpe:/o:redhat:enterprise_linux:8
Red Hat Red Hat Enterprise Linux 8 - cpe:/o:redhat:enterprise_linux:8
Red Hat Red Hat Enterprise Linux 9 - cpe:/o:redhat:enterprise_linux:9
Red Hat Red Hat Enterprise Linux for NVIDIA 26 - cpe:/a:redhat:enterprise_linux_nvidia:
Red Hat Red Hat OpenShift Container Platform 4 - cpe:/a:redhat:openshift:4
Red Hat Red Hat OpenShift Container Platform 4 - cpe:/a:redhat:openshift:4
Red Hat Red Hat OpenStack Platform 13 (Queens) - cpe:/a:redhat:openstack:13

II. Public POCs for CVE-2026-93834

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III. Intelligence Information for CVE-2026-93834

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Other References for CVE-2026-93834 (3)

Same Patch Batch · Red Hat · 2026-09-25 · 3 CVEs total

CVE-2026-97846 6.8 MEDIUM Keycloak-services: keycloak-services: standard token exchange v2 bypasses mtls holder-of-k
CVE-2026-96448 6.6 MEDIUM Keycloak-services: keycloak-services: fgap v2 composite-blind role mapping allows privileg

IV. Related Vulnerabilities

Same product: Red Hat Enterprise Linux 10
Same vendor: Red Hat
Same weakness: CWE-416

V. Comments for CVE-2026-93834

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