What is CVE-2025-39784?

CVE-2025-39784 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 6.13 onward and patched in 6.16.4 and 6.17. CVE-2025-39784 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-39784?

CVE-2025-39784 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2025-39784?

Yes, CVE-2025-39784 has been patched. Fixed versions include 6.16.4 and 6.17. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-39784 actively exploited?

CVE-2025-39784 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-39784

Medium

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]

Package Linux Kernel

Published 2025-09-11

Last modified 2025-11-25

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions

Linux kernel versions 6.13 and later are affected. Fixed in 6.16.4, 6.17 and their respective stable series.

Affected from

≥ 6.13

Fixed in

✓ 6.16.4 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-39784 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/16557320f378262b5c605b15edebd3642406992a
Patch
Kernel patch commit
https://git.kernel.org/stable/c/9989e0ca7462c62f93dbc62f684448aa2efb9226
Patch

Details

CVE ID CVE-2025-39784

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-09-11

Modified 2025-11-25

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-39784?

CVE-2025-39784 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 6.13 onward and has been patched in 6.16.4 and 6.17. CVE-2025-39784 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-39784?

CVE-2025-39784 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2025-39784?

Yes — CVE-2025-39784 has been patched. Fixed versions include 6.16.4 and 6.17. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-39784 actively exploited?

No — CVE-2025-39784 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.