CVE-2025-68208 bpf: account for current allocated stack depth in widen_imprecise_scalars()
A flaw in the Linux kernel BPF verifier allows out-of-bounds stack access, potentially enabling code execution or privilege escalation.
- 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-2025-68208?
CVE-2025-68208 is a high-severity memory corruption vulnerability in Linux, published on 16 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:
bpf: account for current allocated stack depth in widen_imprecise_scalars()
The usage pattern for widen_imprecise_scalars() looks as follows:
prev_st = find_prev_entry(env, ...); queued_st = push_stack(...); widen_imprecise_scalars(env, prev_st, queued_st);
Where prev_st is an ancestor of the queued_st in the explored states tree. This ancestor is not guaranteed to have same allocated stack depth as queued_st. E.g. in the following case:
def main(): for i in 1..2: foo(i) // same callsite, differnt param
def foo(i): if i == 1: use 128 bytes of stack iterator based loop
Here, for a second 'foo' call prev_st->allocated_stack is 128, while queued_st->allocated_stack is much smaller. widen_imprecise_scalars() needs to take this into account and avoid accessing bpf_verifier_state->frame[*]->stack out of bounds.
Which versions are affected by CVE-2025-68208?
How do I fix CVE-2025-68208?
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-2025-68208 being exploited?
There is no known exploitation of CVE-2025-68208 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68208, DEBIAN-CVE-2025-68208, GHSA-2x57-vxvc-jh3v, ROOT-OS-DEBIAN-13-CVE-2025-68208, ROOT-OS-UBUNTU-2404-CVE-2025-68208, UBUNTU-CVE-2025-68208.