VulnerabilityPublished 11 Sep 2025Updated 5 Nov 2026

CVE-2025-39784: Linux kernel · PCI: Fix link speed calculation on retrain failure

Affects Linux kernelSource CVE Database V5

Not known to be exploited : upgrade to 16557320f378262b5c605b15edebd3642406992a or 9989e0ca7462c62f93dbc62f684448aa2efb9226 when convenient.

Data as of 5 Nov 2026, 21:35 UTC

Severity

Low

Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in 16557320f378262b5c605b15edebd3642406992a, 9989e0ca7462c62f93dbc62f684448aa2efb9226

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to 16557320f378262b5c605b15edebd3642406992a or 9989e0ca7462c62f93dbc62f684448aa2efb9226.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ de9a6c8d5dbfedb5eb3722c822da0490f6a59a45, < 16557320f378262b5c605b15edebd3642406992a	Fixed in 16557320f378262b5c605b15edebd3642406992a
LinuxLinux	Affected ≥ de9a6c8d5dbfedb5eb3722c822da0490f6a59a45, < 9989e0ca7462c62f93dbc62f684448aa2efb9226	Fixed in 9989e0ca7462c62f93dbc62f684448aa2efb9226
LinuxLinux	Affected =6.13	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel. Users should update to the fixed kernel versions identified by the commits 16557320f378262b5c605b15edebd3642406992a and 9989e0ca7462c62f93dbc62f684448aa2efb9226. No additional mitigation is required beyond applying the official patch.

Description

A vulnerability in the Linux kernel PCI subsystem caused incorrect link speed calculations during PCIe link retrain failures. This occurs because the code did not properly mask non-speed bits when reading the Link Control 2 register, resulting in an invalid speed value that triggers kernel warnings. The issue has been fixed by correcting the masking logic to prevent erroneous speed values.

Impact

The vulnerability causes incorrect PCIe link speed reporting and kernel warnings during link retrain failures. This may result in degraded PCIe device functionality or instability due to improper handling of link speeds. There is no indication of direct security compromise or exploitation in the wild.

Summary

CVE-2025-39784 addresses a flaw in the Linux kernel's PCIe link retrain failure handling. When the function pcie_failed_link_retrain() fails to retrain a PCIe link, it attempts to revert to the previous link speed by reading the Link Control 2 register. However, it failed to mask out non-speed bits before converting the register value, causing the conversion macro PCIE_LNKCTL2_TLS2SPEED() to return PCI_SPEED_UNKNOWN (0xff). This leads to kernel warnings in pcie_set_target_speed() and indicates broken device behavior. The fix involves masking out non-speed bits in both PCIE_LNKCTL2_TLS2SPEED() and PCIE_LNKCAP_SLS2SPEED() macros to ensure correct speed calculation and prevent warnings.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Nov 2026, 21:35 UTC

Technical details

References

Community reviews

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