In the Linux kernel, the following vulnerability has been resolved:
net: Only allow init netns to set default tcp cong to a restricted algo
tcp_set_default_congestion_control() is netns-safe in that it writes to &net->ipv4.tcp_congestion_control, but it also sets ca->flags |= TCP_CONG_NON_RESTRICTED which is not namespaced. This has the unintended side-effect of changing the global net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control readonly in non-init netns")
Resolve this netns "leak" by only allowing the init netns to set the default algorithm to one that is restricted. This restriction could be removed if tcp_allowed_congestion_control were namespace-ified in the future.
This bug was uncovered with https://github.com/JonathonReinhart/linux-netns-sysctl-verify
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade bpftoolUpgrade kernel-headersUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfoUpgrade kernelUpgrade kernel-tools-develUpgrade python-perf-debuginfoUpgrade kernel-tools-debuginfoUpgrade kernel-develUpgrade kernel-toolsUpgrade bpftool-debuginfoUpgrade python-perfUpgrade perfUpgrade perf-debuginfoUpgrade kernel-debuginfo-common-aarch64 | Jun 11, 2024 | Feb 28, 2024 |
| Debian | — | Upgrade linux | Jul 30, 2024 | Feb 28, 2024 |
| Huawei Euleros 2_0_sp8 | — | Upgrade kernel-headersUpgrade python3-perfUpgrade kernel-develUpgrade kernelUpgrade kernel-toolsUpgrade python-perfUpgrade bpftoolUpgrade kernel-tools-libsUpgrade perf | Jul 23, 2024 | Feb 28, 2024 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | Feb 28, 2024 |
| Ubuntu | — | Upgrade linux-kvmUpgrade linux-gkeopUpgrade linux-fipsUpgrade linux-hweUpgrade linux-hwe-5.4Upgrade linux-oracleUpgrade linux-gcp-5.4Upgrade linux-aws-fipsUpgrade linux-gcpUpgrade linux-gcp-fipsUpgrade linux-azure-fipsUpgrade linux-azureUpgrade linux-gcp-4.15Upgrade linux-azure-5.4Upgrade linux-azure-4.15Upgrade linux-aws-hweUpgrade linux-aws-5.4Upgrade linux-raspi-5.4Upgrade linux-awsUpgrade linux-bluefieldUpgrade linux-raspiUpgrade linuxUpgrade linux-oracle-5.4 | Nov 19, 2024 | Feb 28, 2024 |
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