CVE-2025-21972 net: mctp: unshare packets when reassembling
A memory leak in the Linux kernel MCTP reassembly logic can lead to denial of service when packets are cloned.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21972?
CVE-2025-21972 is a high-severity memory corruption vulnerability in Linux kernel, published on 1 Apr 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:
net: mctp: unshare packets when reassembling
Ensure that the frag_list used for reassembly isn't shared with other packets. This avoids incorrect reassembly when packets are cloned, and prevents a memory leak due to circular references between fragments and their skb_shared_info.
The upcoming MCTP-over-USB driver uses skb_clone which can trigger the problem - other MCTP drivers don't share SKBs.
A kunit test is added to reproduce the issue.
Weakness: CWE-401
Which versions are affected by CVE-2025-21972?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21972?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-21972 being exploited?
There is no known exploitation of CVE-2025-21972 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21972, DEBIAN-CVE-2025-21972, GHSA-w7xc-x24c-mg52, ROOT-OS-DEBIAN-12-CVE-2025-21972, ROOT-OS-UBUNTU-2204-CVE-2025-21972, ROOT-OS-UBUNTU-2404-CVE-2025-21972 and 1 more.