CVE-2026-93125 bpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max
A missing bounds check in the Linux kernel BPF verifier allows integer truncation, potentially leading to memory corruption and 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-2026-93125?
CVE-2026-93125 is a high-severity vulnerability in Linux, published on 17 Sep 2026. 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: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max
check_kfunc_args() detects a kfunc argument named rdonly_buf_size or rdwr_buf_size and stores reg->var_off.value into meta->r0_size, a u64, and does not bound it. check_kfunc_call() later copies that value into the returned register's mem_size field:
meta->r0_size = reg->var_off.value; ... regs[BPF_REG_0].mem_size = meta.r0_size;
regs[BPF_REG_0].mem_size is u32. A constant whose upper 32 bits are set gets truncated instead of causing a load-time rejection, so the verifier records a PTR_TO_MEM register with an approximately 4 GiB mem_size for whatever allocation the kfunc returned. A later access check against that register uses the truncated, wrong bound.
Reject rdonly_buf_size/rdwr_buf_size values that exceed U32_MAX at the point meta->r0_size is set.
Which versions are affected by CVE-2026-93125?
How do I fix CVE-2026-93125?
Apply the vendor's patch.
Is CVE-2026-93125 being exploited?
There is no known exploitation of CVE-2026-93125 in the wild and no public exploit code.
Sources
Also known as AZL-101876, BELL-CVE-2026-93125, DEBIAN-CVE-2026-93125, GHSA-vqq3-2x9h-9pmg, UBUNTU-CVE-2026-93125.