# CVE-2025-39784: linux: In the Linux kernel, the following vulnerability has been resolved:  PCI: Fix link speed calculation on retrain failu...

CVE-2025-39784 is fixed in linux on 1 platform by DEBIAN-CVE-2025-39784 (version 6.16.5-1), released September 11, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-39784
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 11, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  PCI: Fix link speed calculation on retrain failure  When pcie_failed_link_retrain() fails to retrain, it tries to revert to the previous link speed.  However it calculates that speed from the Link Control 2 register without masking out non-speed bits first.  PCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to PCI_SPEED_UNKNOWN (0xff), which in turn causes a WARN splat in pcie_set_target_speed():    pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port   pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s   pci 0000:00:01.1: retraining failed   WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed   RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000   pcie_failed_link_retrain   pci_device_add   pci_scan_single_device  Mask out the non-speed bits in PCIE_LNKCTL2_TLS2SPEED() and PCIE_LNKCAP_SLS2SPEED() so they don't incorrectly return PCI_SPEED_UNKNOWN.  [bhelgaas: commit log, add details from https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.16.5-1 | [DEBIAN-CVE-2025-39784](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39784.md) | Sep 11, 2025 |

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