CVE-2026-98627 bpf: Preserve packet pointer class displacement in regsafe()
A flaw in the Linux kernel BPF verifier allows out-of-bounds packet access, potentially leading to memory corruption and privilege escalation for local attackers.
- 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-2026-98627?
CVE-2026-98627 is a memory corruption vulnerability in Linux, published on 18 Oct 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: Preserve packet pointer class displacement in regsafe()
regsafe() maps packet pointer IDs between states and checks that each current register range is a subset of the corresponding explored register range. It does not, however, preserve the displacement between registers that share a packet pointer ID.
This is unsound because packet range is shared by ID. A bounds check on one class member updates every member, and a later access can consume the range through another member. Commit 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers") folded the fixed pointer offset into r64 and removed the old off equality check, so two individually narrower registers can prune even when their displacement has changed. The explored path can then license an out-of-bounds packet access on the pruned path.
Require matching range bases for packet pointers with an ID. Together with the existing ID mapping, this preserves the displacement between members of each packet-pointer class without adding per-ID state. Packet pointers without an ID remain unaffected.
Which versions are affected by CVE-2026-98627?
How do I fix CVE-2026-98627?
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-2026-98627 being exploited?
There is no known exploitation of CVE-2026-98627 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-98627, GHSA-p3gw-45vq-6cwq, UBUNTU-CVE-2026-98627.