CVE-2026-53036 bpf, arm64: Fix off-by-one in check_imm signed range check
An off-by-one error in the Linux kernel's arm64 BPF JIT allows branch displacement overflow, potentially leading to arbitrary 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-2026-53036?
CVE-2026-53036 is a high-severity vulnerability in Linux kernel, published on 24 Jun 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, arm64: Fix off-by-one in check_imm signed range check
check_imm(bits, imm) is used in the arm64 BPF JIT to verify that a branch displacement (in arm64 instruction units) fits into the signed N-bit immediate field of a B, B.cond or CBZ/CBNZ encoding before it is handed to the encoder. The macro currently tests for (imm > 0 && imm >> bits) || (imm < 0 && ~imm >> bits) which admits values in [-2^N, 2^N) — effectively a signed (N+1)-bit range. A signed N-bit field only holds [-2^(N-1), 2^(N-1)), so the check admits one extra bit of range on each side.
In particular, for check_imm19(), values in [2^18, 2^19) slip past the check but do not fit into the 19-bit signed imm19 field of B.cond. aarch64_insn_encode_immediate() then masks the raw value into the 19-bit field, setting bit 18 (the sign bit) and flipping a forward branch into a backward one. Same class of issue exists for check_imm26() and the B/BL encoding. Shift by (bits - 1) instead of bits so the actual signed N-bit range is enforced.
Weakness: CWE-193
Which versions are affected by CVE-2026-53036?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53036?
Apply the vendor's patch.
Is CVE-2026-53036 being exploited?
There is no known exploitation of CVE-2026-53036 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53036, DEBIAN-CVE-2026-53036, GHSA-mfc2-6j6q-99vp, ROOT-OS-DEBIAN-11-CVE-2026-53036, ROOT-OS-DEBIAN-12-CVE-2026-53036, ROOT-OS-UBUNTU-2204-CVE-2026-53036 and 2 more.