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.
総合評価: CVE-2021-3748 は中リスク（44.6/100）。CVSS 深刻度は高。悪用される可能性が高い（EPSS 0.53%、40 パーセンタイル） 推奨対応: 影響資産を整理し、修補計画に組み込んでください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置（高いほど相対的に深刻）を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ（新 − 旧） |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.03% | 0.53% | +0.50% |
| 2 | 2025-11-21 | 0.10% | 0.03% | -0.07% |
| 3 | 2025-11-18 | — | 0.10% | — |
EPSS の全履歴 （全 8 件）
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
0.8 | 6.0 | [email protected] |
| 6.9 | 2.0 | MEDIUM |
|
3.4 | 10.0 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
high | CVE-2021-3748: 1 source package rows (qemu); 23 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 23. | https://security.alpinelinux.org/vuln/CVE-2021-3748 |
debian
|
not yet assigned | CVE-2021-3748 not yet assigned priority: Debian including 1 source packages (qemu), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2021-3748 |
gentoo
|
high | CVE-2021-3748: 1 GLSA(s) (202208-27), 1 atom(s) (app-emulation/qemu); latest impact high. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3748 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2021-3748 |
suse
|
medium | CVE-2021-3748 severity moderate: SUSE including 781 source package names (0.45.0.7.7.56:qemu-5.2.0-106.4, 0.45.0.7.7.56:qemu-ipxe-1.0.0+-106.4, …), 1272 product×package rows across 65 product lines (Container suse/sle-micro-rancher/5.2, Container suse/sles/15.3/libguestfs-tools, … (65 product lines)): Fixed 1046, Known Affected 225, Known Not Affected 1. | https://www.suse.com/security/cve/CVE-2021-3748/ |
ubuntu
|
medium | CVE-2021-3748 medium priority: Ubuntu including 1 source packages (qemu), 9 status rows across 9 suites (bionic, focal, hirsute, impish, jammy, kinetic, trusty, upstream, xenial): released 5, not-affected 2, ignored 1, needs-triage 1. | https://ubuntu.com/security/CVE-2021-3748 |
| ベンダー | 製品 | バージョン | 生の CPE |
|---|---|---|---|
| qemu | qemu | >= 0.10.0, < 6.2.0 | cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:* |
| debian | debian_linux | 9.0 | cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* |
| debian | debian_linux | 10.0 | cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* |
| canonical | ubuntu_linux | 18.04 | cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* |
| canonical | ubuntu_linux | 20.04 | cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:* |
| canonical | ubuntu_linux | 21.10 | cpe:2.3:o:canonical:ubuntu_linux:21.10:*:*:*:*:*:*:* |
| fedoraproject | fedora | 34 | cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* |
| redhat | enterprise_linux | 8.0 | cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:* |
| redhat | enterprise_linux_advanced_virtualization_eus | 8.4 | cpe:2.3:o:redhat:enterprise_linux_advanced_virtualization_eus:8.4:*:*:*:*:*:*:* |
| URL | タグ |
|---|---|
| https://bugzilla.redhat.com/show_bug.cgi?id=1998514 | Issue Tracking Patch Third Party Advisory |
| https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6 | Patch Third Party Advisory |
| https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html | Mailing List Third Party Advisory |
| https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html | Mailing List Third Party Advisory |
| https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.html | Mailing List Patch Third Party Advisory |
| https://security.gentoo.org/glsa/202208-27 | Third Party Advisory |
| https://security.netapp.com/advisory/ntap-20220425-0004/ | Third Party Advisory |
| https://ubuntu.com/security/CVE-2021-3748 | Patch Third Party Advisory |