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Vulnerability · Published Feb 28, 2024 · Assigned by Linux

CVE-2021-47010net: Only allow init netns to set default tcp cong to a restricted algo

High 7.8

In plain English

A high-severity uncontrolled resource consumption in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.3%top 82.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux5.10.38-1DEBIAN-CVE-2021-47010
Debian:13linux5.10.38-1DEBIAN-CVE-2021-47010
Debian:14linux5.10.38-1DEBIAN-CVE-2021-47010
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2021-47010
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2021-47010
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2021-47010

Affected products (as reported)

VendorProductVersions
Linux Linux 6670e152447732ba90626f36dfc015a13fbf150e – before 992de06308d9a9584d59b96d294ac676f924e4376670e152447732ba90626f36dfc015a13fbf150e – before 9884f745108f7d25b189bbcd6754e284fb29ab686670e152447732ba90626f36dfc015a13fbf150e – before 6c1ea8bee75df8fe2184a50fcd0f70bf82986f426670e152447732ba90626f36dfc015a13fbf150e – before efe1532a6e1a8e3c343d04fff510f0ed80328f9c6670e152447732ba90626f36dfc015a13fbf150e – before e7d7bedd507bb732e600403b7a96f9fe48d0ca316670e152447732ba90626f36dfc015a13fbf150e – before 8d432592f30fcc34ef5a10aac4887b4897884493
Linux Linux 4.15

Weakness: CWE-400 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References