CVE-2021-47010 net: Only allow init netns to set default tcp cong to a restricted algo
A Linux kernel flaw allowed non-init network namespaces to bypass restrictions on TCP congestion control algorithms, altering global read-only settings.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47010?
CVE-2021-47010 is a high-severity vulnerability in Linux kernel, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.
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
Weakness: CWE-400
Which versions are affected by CVE-2021-47010?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47010?
Apply the vendor's patch.
Is CVE-2021-47010 being exploited?
There is no known exploitation of CVE-2021-47010 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47010, GHSA-c8v5-2jcx-x4j2, UBUNTU-CVE-2021-47010.