# 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.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 5 Aug 2026
- **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, ROOT-OS-UBUNTU-2404-CVE-2026-53036, UBUNTU-CVE-2026-53036

## 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 (Off-by-one Error)

## Which versions are affected by CVE-2026-53036?

It affects 1 product.


Products: 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53036 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-53036 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53036/ (Markdown: https://insights.sbomify.com/CVE-2026-53036/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53036
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53036
- OSV: https://osv.dev/vulnerability/CVE-2026-53036

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53036/
Summaries are generated and may contain mistakes; the official description above is the record.