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
02 Description
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
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 0.33% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 26.2% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-05-13 15:24Z5 YR AGO
- Last updated
- 2024-08-03 17:30Z2 YR AGO
- Reserved
- 2020-12-17
- Assigning CNA
- redhat
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- Data version
- 5.1
- Document digest
- 9d8a3e9ed083e2c1ce976c323e9ce567738692bbbdba61dfb32083eed9b6e13f
05 Affected products
06 References
- www.zerodayinitiative.comhttps://www.zerodayinitiative.com/advisories/ZDI-21-159/
- lists.debian.org[debian-lts-announce] 20210218 [SECURITY] [DLA 2560-1] qemu security updatehttps://lists.debian.org/debian-lts-announce/2021/02/msg00024.html
- bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=1927007
- security.netapp.comhttps://security.netapp.com/advisory/ntap-20210720-0009/
- lists.debian.org[debian-lts-announce] 20220905 [SECURITY] [DLA 3099-1] qemu security updatehttps://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
07 Fixed in
Debian 12
- qemu Fixed in 1:5.2+dfsg-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- qemu Fixed in 1:5.2+dfsg-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- qemu Fixed in 1:5.2+dfsg-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 16.04 LTS
- qemu Fixed in 1:2.5+dfsg-5ubuntu10.49
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- qemu Fixed in 1:2.11+dfsg-1ubuntu7.35
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- qemu Fixed in 1:4.2-3ubuntu6.12
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 14.04 LTS
- qemu Fixed in 2.0.0+dfsg-2ubuntu1.47+esm6Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.