CVE-2024-49974 NFSD: Limit the number of concurrent async COPY operations
Unlimited concurrent async COPY operations in the Linux kernel NFSD allow attackers to cause a denial of service.
- 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-2024-49974?
CVE-2024-49974 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 Oct 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:
NFSD: Limit the number of concurrent async COPY operations
Nothing appears to limit the number of concurrent async COPY operations that clients can start. In addition, AFAICT each async COPY can copy an unlimited number of 4MB chunks, so can run for a long time. Thus IMO async COPY can become a DoS vector.
Add a restriction mechanism that bounds the number of concurrent background COPY operations. Start simple and try to be fair -- this patch implements a per-namespace limit.
An async COPY request that occurs while this limit is exceeded gets NFS4ERR_DELAY. The requesting client can choose to send the request again after a delay or fall back to a traditional read/write style copy.
If there is need to make the mechanism more sophisticated, we can visit that in future patches.
Which versions are affected by CVE-2024-49974?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-49974?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-49974 being exploited?
There is no known exploitation of CVE-2024-49974 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-52062, AZL-52116, BELL-CVE-2024-49974, DEBIAN-CVE-2024-49974, GHSA-4xwj-gw53-4w3v, UBUNTU-CVE-2024-49974.