Time-of-check time-of-use race condition in qemu
Priority LOW 33CWE-367Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- High
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
A race condition flaw was found in the 9pfs server implementation of QEMU up to and including 5.2.0. This flaw allows a malicious 9p client to cause a use-after-free error, potentially escalating their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity as well as system availability.
Why it matters now
EPSS 0.00333 26th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | qemu | up to, including 5.2.0 | — | No fix listed | CNA |
- qemu Vendor— Affected up to, including 5.2.0 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 8 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 8 Advanced Virtualization
- Red Hat Enterprise Linux 9
- Red Hat OpenStack Platform 10 (Newton)
- Red Hat OpenStack Platform 13 (Queens)
- Red Hat Virtualization 4
Timeline
- 2026-10-02 Threatist record created from CVE-2021-20181
- 2026-10-03 Alias added: GHSA-mq7v-47j3-rc24
References
Sources
- CVE-2021-20181 · CVE Program
- CVE-2021-20181 · NVD
- FIRST EPSS
- GHSA-mq7v-47j3-rc24 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-20181 · Red Hat security data · CC BY 4.0
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