critical
CVE-2021-3773
kernel: lack of port sanity checking in natd and netfilter leads to exploit of OpenVPN clients
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.
Severity by source
NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Trivy's own label is CRITICAL. Rated critical by NVD, CBL-Mariner. Rated lower by AlmaLinux (high), Oracle (high), Red Hat (medium).
Description
A flaw in netfilter could allow a network-connected attacker to infer openvpn connection endpoint information for further use in traditional network attacks.
Affected packages and fixed versions
| Source | Package | Fixed in |
|---|---|---|
| CBL-Mariner 1.0 | kernel | no fix listed |
| alma 8 | bpftool, kernel, kernel-abi-stablelists and 17 more | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | bpftool, kernel, kernel-abi-stablelists and 17 more | 4.18.0-372.9.1.el8 |
| Red Hat | bpftool, kernel, kernel-abi-whitelists and 24 more | no fix listed |
| rocky 8 | bpftool, kernel, kernel-abi-stablelists and 18 more | 4.18.0-372.9.1.el8 and 1 more |
Show all 89 entries from 5 sources
| Source | Package | Fixed in |
|---|---|---|
| CBL-Mariner 1.0 | kernel | no fix listed |
| alma 8 | bpftool | 4.18.0-372.9.1.el8 |
| alma 8 | kernel | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-abi-stablelists | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-core | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-cross-headers | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-debug | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-debug-core | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-debug-devel | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-debug-modules | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-debug-modules-extra | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-devel | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-doc | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-headers | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-modules | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-modules-extra | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-tools | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-tools-libs | 4.18.0-372.9.1.el8 |
| alma 8 | kernel-tools-libs-devel | 4.18.0-372.9.1.el8 |
| alma 8 | perf | 4.18.0-372.9.1.el8 |
| alma 8 | python3-perf | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | bpftool | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-abi-stablelists | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-core | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-cross-headers | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-debug | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-debug-core | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-debug-devel | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-debug-modules | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-debug-modules-extra | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-devel | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-doc | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-headers | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-modules | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-modules-extra | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-tools | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-tools-libs | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | kernel-tools-libs-devel | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | perf | 4.18.0-372.9.1.el8 |
| Oracle Linux 8 | python3-perf | 4.18.0-372.9.1.el8 |
| Red Hat | bpftool | no fix listed |
| Red Hat | kernel | no fix listed |
| Red Hat | kernel-abi-whitelists | no fix listed |
| Red Hat | kernel-bootwrapper | no fix listed |
| Red Hat | kernel-debug | no fix listed |
| Red Hat | kernel-debug-devel | no fix listed |
| Red Hat | kernel-devel | no fix listed |
| Red Hat | kernel-doc | no fix listed |
| Red Hat | kernel-firmware | no fix listed |
| Red Hat | kernel-headers | no fix listed |
| Red Hat | kernel-kdump | no fix listed |
| Red Hat | kernel-kdump-devel | no fix listed |
| Red Hat | kernel-rt | no fix listed |
| Red Hat | kernel-rt-debug | no fix listed |
| Red Hat | kernel-rt-debug-devel | no fix listed |
| Red Hat | kernel-rt-debug-kvm | no fix listed |
| Red Hat | kernel-rt-devel | no fix listed |
| Red Hat | kernel-rt-doc | no fix listed |
| Red Hat | kernel-rt-kvm | no fix listed |
| Red Hat | kernel-rt-trace | no fix listed |
| Red Hat | kernel-rt-trace-devel | no fix listed |
| Red Hat | kernel-rt-trace-kvm | no fix listed |
| Red Hat | kernel-tools | no fix listed |
| Red Hat | kernel-tools-libs | no fix listed |
| Red Hat | kernel-tools-libs-devel | no fix listed |
| Red Hat | perf | no fix listed |
| Red Hat | python-perf | no fix listed |
| rocky 8 | bpftool | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-abi-stablelists | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-core | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-cross-headers | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debug | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debug-core | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debug-devel | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debug-modules | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debug-modules-extra | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-debuginfo-common-aarch64 | 0.0.0 |
| rocky 8 | kernel-debuginfo-common-x86_64 | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-devel | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-doc | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-headers | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-modules | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-modules-extra | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-tools | 4.18.0-372.9.1.el8 |
| rocky 8 | kernel-tools-libs | 4.18.0-372.9.1.el8 |
| rocky 8 | perf | 4.18.0-372.9.1.el8 |
| rocky 8 | python3-perf | 4.18.0-372.9.1.el8 |
References
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-0404.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-13974.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-27820.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-4788.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-0941.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20322.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-21781.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-26401.json
All 48 references
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-29154.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3612.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3669.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-37159.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3743.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3744.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3752.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3759.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3764.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3772.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3773.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4002.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4037.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4083.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4157.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-41864.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4197.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-4203.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-42739.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-43056.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-43389.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-43976.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-44733.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-45485.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-45486.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2022-0001.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2022-0002.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2022-0286.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2022-0322.json
- https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2022-1011.json
- https://access.redhat.com/security/cve/CVE-2021-3773
- https://bugzilla.redhat.com/show_bug.cgi?id=2004949
- https://citizenlab.ca/2024/07/vulnerabilities-in-vpns-paper-presented-at-the-privacy-enhancing-technologies-symposium-2024/
- https://errata.almalinux.org/8/ALSA-2022-1988.html
- https://linux.oracle.com/cve/CVE-2021-3773.html
- https://linux.oracle.com/errata/ELSA-2022-1988.html
- https://nvd.nist.gov/vuln/detail/CVE-2021-3773
- https://security.netapp.com/advisory/ntap-20250328-0004/
- https://www.cve.org/CVERecord?id=CVE-2021-3773
- https://www.oracle.com/security-alerts/cpujul2022.html