CVE-2023-53669 tcp: fix skb_copy_ubufs() vs BIG TCP
A flaw in the Linux kernel TCP stack causes crashes when handling large packets with zerocopy, leading to 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-2023-53669?
CVE-2023-53669 is a high-severity denial of service vulnerability in Linux kernel, published on 7 Oct 2025. 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:
tcp: fix skb_copy_ubufs() vs BIG TCP
David Ahern reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy using hugepages, and skb length bigger than ~68 KB.
skb_copy_ubufs() assumed it could copy all payload using up to MAX_SKB_FRAGS order-0 pages.
This assumption broke when BIG TCP was able to put up to 512 KB per skb.
We did not hit this bug at Google because we use CONFIG_MAX_SKB_FRAGS=45 and limit gso_max_size to 180000.
A solution is to use higher order pages if needed.
v2: add missing __GFP_COMP, or we leak memory.
Weakness: CWE-401
Which versions are affected by CVE-2023-53669?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53669?
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-2023-53669 being exploited?
There is no known exploitation of CVE-2023-53669 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53669, DEBIAN-CVE-2023-53669, GHSA-3p8v-593f-mgx8, UBUNTU-CVE-2023-53669.