Vulnerability Details : CVE-2021-20181
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.
Vulnerability category: Memory Corruption
Exploit prediction scoring system (EPSS) score for CVE-2021-20181
Probability of exploitation activity in the next 30 days: 0.05%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 15 % EPSS Score History EPSS FAQ
CVSS scores for CVE-2021-20181
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source |
|---|---|---|---|---|---|
|
6.9
|
MEDIUM | AV:L/AC:M/Au:N/C:C/I:C/A:C |
3.4
|
10.0
|
NIST |
|
7.5
|
HIGH | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H |
0.8
|
6.0
|
NIST |
CWE ids for CVE-2021-20181
-
The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.Assigned by: nvd@nist.gov (Primary)
-
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.Assigned by: secalert@redhat.com (Secondary)
-
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.Assigned by: secalert@redhat.com (Secondary)
References for CVE-2021-20181
-
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
[SECURITY] [DLA 3099-1] qemu security updateMailing List;Third Party Advisory
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https://lists.debian.org/debian-lts-announce/2021/02/msg00024.html
[SECURITY] [DLA 2560-1] qemu security updateMailing List;Third Party Advisory
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https://bugzilla.redhat.com/show_bug.cgi?id=1927007
1927007 – (CVE-2021-20181) CVE-2021-20181 qemu: 9pfs: TOCTOU privilege escalation vulnerabilityIssue Tracking;Patch;Third Party Advisory
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https://www.zerodayinitiative.com/advisories/ZDI-21-159/
ZDI-21-159 | Zero Day InitiativeThird Party Advisory;VDB Entry
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https://security.netapp.com/advisory/ntap-20210720-0009/
CVE-2021-20181 QEMU Vulnerability in NetApp Products | NetApp Product SecurityThird Party Advisory
Products affected by CVE-2021-20181
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
- cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*