CVE-2023-54039 can: j1939: j1939_tp_tx_dat_new(): fix out-of-bounds memory access
An out-of-bounds memory access in the Linux kernel J1939 CAN protocol allows attackers to cause denial of service or potentially execute code.
- 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-2023-54039?
CVE-2023-54039 is a memory corruption vulnerability in Linux, published on 24 Dec 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:
can: j1939: j1939_tp_tx_dat_new(): fix out-of-bounds memory access
In the j1939_tp_tx_dat_new() function, an out-of-bounds memory access could occur during the memcpy() operation if the size of skb->cb is larger than the size of struct j1939_sk_buff_cb. This is because the memcpy() operation uses the size of skb->cb, leading to a read beyond the struct j1939_sk_buff_cb.
Updated the memcpy() operation to use the size of struct j1939_sk_buff_cb instead of the size of skb->cb. This ensures that the memcpy() operation only reads the memory within the bounds of struct j1939_sk_buff_cb, preventing out-of-bounds memory access.
Additionally, add a BUILD_BUG_ON() to check that the size of skb->cb is greater than or equal to the size of struct j1939_sk_buff_cb. This ensures that the skb->cb buffer is large enough to hold the j1939_sk_buff_cb structure.
[mkl: rephrase commit message]
Which versions are affected by CVE-2023-54039?
How do I fix CVE-2023-54039?
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-2023-54039 being exploited?
There is no known exploitation of CVE-2023-54039 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54039, DEBIAN-CVE-2023-54039, GHSA-3q37-wmq7-mf4x, UBUNTU-CVE-2023-54039.