CVE-2026-98590 bpf: Fix bpf_sock context code generation
A flaw in Linux kernel BPF socket context code generation allows local attackers to bypass verifier checks, potentially leading to privilege escalation or code execution.
- 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-2026-98590?
CVE-2026-98590 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: Fix bpf_sock context code generation
Currently, the ctx access code reads the rx_queue_mapping field with either a 4-byte or 2-byte load. The rest of the bits in the register are marked known zero by the verifier. However, the emitted ctx access code places in the register on certain the special value (-1) using BPF_MOV_IMM64, which gets sign-extended to turn on all the bits in the register. By shifting this value right, the program ends up with a value at runtime above what the verifier assumes is possible.
Fix this by ensuring the read value is as wide as the assumed size. Use MOV32 instructions instead of MOV64 instructions to keep the upper bits zero as assumed by the verifier. Also properly report the size of the destination variable (the bpf_sock field, 4 bytes) instead of the source (the socket field, 2 bytes).
Which versions are affected by CVE-2026-98590?
How do I fix CVE-2026-98590?
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-2026-98590 being exploited?
There is no known exploitation of CVE-2026-98590 in the wild and no public exploit code.
Sources
Also known as AZL-109410, BELL-CVE-2026-98590, DEBIAN-CVE-2026-98590, GHSA-6ffg-3w9m-mjpv, UBUNTU-CVE-2026-98590.