CVE-2021-3748: Use After Free
First published: Fri Aug 27 2021(Updated: )
A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor's address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a denial of service condition, or potentially execute code on the host with the privileges of the QEMU process.
Credit: secalert@redhat.com secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| QEMU qemu | >=0.10.0<6.2.0 | |
| Debian Debian Linux | =9.0 | |
| Debian Debian Linux | =10.0 | |
| Canonical Ubuntu Linux | =18.04 | |
| Canonical Ubuntu Linux | =20.04 | |
| Canonical Ubuntu Linux | =21.10 | |
| Fedoraproject Fedora | =34 | |
| Redhat Enterprise Linux | =8.0 | |
| Redhat Enterprise Linux Advanced Virtualization Eus | =8.4 | |
| ubuntu/qemu | <1:6.0+dfsg-2 | 1:6.0+dfsg-2 |
| ubuntu/qemu | <1:6.2+dfsg-2ubuntu5 | 1:6.2+dfsg-2ubuntu5 |
| ubuntu/qemu | <1:2.11+dfsg-1ubuntu7.39 | 1:2.11+dfsg-1ubuntu7.39 |
| ubuntu/qemu | <1:4.2-3ubuntu6.21 | 1:4.2-3ubuntu6.21 |
| ubuntu/qemu | <1:6.2+dfsg-2ubuntu5 | 1:6.2+dfsg-2ubuntu5 |
| redhat/qemu-kvm | <6.2.0 | 6.2.0 |
| debian/qemu | <=1:3.1+dfsg-8+deb10u8 | 1:3.1+dfsg-8+deb10u11 1:5.2+dfsg-11+deb11u3 1:5.2+dfsg-11+deb11u2 1:7.2+dfsg-7+deb12u3 1:8.2.1+ds-1 |
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Reference Links
- https://security-tracker.debian.org/tracker/CVE-2021-3748
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3748
- https://bugzilla.redhat.com/show_bug.cgi?id=1998514
- https://security-tracker.debian.org/tracker/CVE-2021-3638
- https://security-tracker.debian.org/tracker/CVE-2021-3682
- https://security-tracker.debian.org/tracker/CVE-2021-3713
- https://security-tracker.debian.org/tracker/CVE-2021-3544
- https://security-tracker.debian.org/tracker/CVE-2021-3545
- https://security-tracker.debian.org/tracker/CVE-2021-3546
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=993401
- https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6
- https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.html
- https://ubuntu.com/security/CVE-2021-3748
- https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html
- https://security.netapp.com/advisory/ntap-20220425-0004/
- https://security.gentoo.org/glsa/202208-27
- https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html
- https://launchpad.net/bugs/cve/CVE-2021-3748
- https://gitlab.com/qemu-project/qemu/-/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6
- https://gitlab.com/qemu-project/qemu/-/issues/535
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1998514#c4
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1998514#c0
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1999212
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1999211
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1999213
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1998514#c5
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1998514#c8
- https://www.qemu.org/contribute/security-process
- https://access.redhat.com/solutions/408653
- https://access.redhat.com/errata/RHSA-2021:4112
- https://access.redhat.com/security/cve/cve-2021-3748
- https://access.redhat.com/errata/RHSA-2021:5036
- https://access.redhat.com/errata/RHSA-2022:1759
- https://ubuntu.com/security/notices/USN-5307-1
- https://nvd.nist.gov/vuln/detail/CVE-2021-3748
- https://git.qemu.org/?p=qemu.git;a=commit;h=bedd7e93d01961fcb16a97ae45d93acf357e11f6
Frequently Asked Questions
What is the vulnerability ID for this use-after-free vulnerability?
The vulnerability ID for this use-after-free vulnerability is CVE-2021-3748.
What is the severity level of CVE-2021-3748?
The severity level of CVE-2021-3748 is high with a severity value of 7.5.
Which software is affected by CVE-2021-3748?
The affected software includes QEMU, qemu-kvm, Debian Linux, Ubuntu Linux, Fedora, and Red Hat Enterprise Linux.
How can a malicious guest exploit CVE-2021-3748?
A malicious guest can exploit CVE-2021-3748 to crash QEMU by causing a use-after-free vulnerability in the virtio-net device.
Where can I find more information about CVE-2021-3748?
You can find more information about CVE-2021-3748 on the QEMU mailing list and GitLab repositories.
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