# CVE-2026-53300: linux: In the Linux kernel, the following vulnerability has been resolved:  net: enetc: fix NTMP DMA use-after-free issue  T...

CVE-2026-53300 is fixed in linux on 1 platform by DEBIAN-CVE-2026-53300 (version 7.0.10-1), released June 27, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-53300
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 26, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  net: enetc: fix NTMP DMA use-after-free issue  The AI-generated review reported a potential DMA use-after-free issue [1]. If netc_xmit_ntmp_cmd() times out and returns an error, the pending command is not explicitly aborted, while ntmp_free_data_mem() unconditionally frees the DMA buffer. If the buffer has already been reallocated elsewhere, this may lead to silent memory corruption. Because the hardware eventually processes the pending command and perform a DMA write of the response to the physical address of the freed buffer.  To resolve this issue, this patch does the following modifications:  1. Convert cbdr->ring_lock from a spinlock to a mutex  The lock was originally a spinlock in case NTMP operations might be invoked from atomic context. After downstream support for all NTMP tables, no such usage has materialized. A mutex lock is now required because the driver now needs to reclaim used BDs and release associated DMA memory within the lock's context, while dma_free_coherent() might sleep.  2. Introduce software command BD (struct netc_swcbd)  The hardware write-back overwrites the addr and len fields of the BD, so the driver cannot rely on the hardware BD to free the associated DMA memory. The driver now maintains a software shadow BD storing the DMA buffer pointer, DMA address, and size. And netc_xmit_ntmp_cmd() only reclaims older BDs when the number of used BDs reaches NETC_CBDR_CLEAN_WORK (16). The software BD enables correct DMA memory release. With this, struct ntmp_dma_buf and ntmp_free_data_mem() are no longer needed and are removed.  3. Require callers to hold ring_lock across netc_xmit_ntmp_cmd()  netc_xmit_ntmp_cmd() releases the ring_lock before the caller finishes consuming the response. At this point, if a concurrent thread submits a new command, it may trigger ntmp_clean_cbdr() and free the DMA buffer while it is still in use. Move ring_lock ownership to the caller to ensure the response buffer cannot be reclaimed prematurely. So the helpers ntmp_select_and_lock_cbdr() and ntmp_unlock_cbdr() are added.  These changes eliminate the DMA use-after-free condition and ensure safe and consistent BD reclamation and DMA buffer lifecycle management.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.0.10-1 | [DEBIAN-CVE-2026-53300](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53300.md) | Jun 27, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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