VulnerabilityPublished 18 Oct 2026

CVE-2026-98563: Linux kernel · net: phylink: record the PHY only once bringup cannot fail

Source GCVE Database

Authoritative record:CVE-2026-98563· Medium

Not known to be exploited · fixed in a940003f44e7e441c228151dd212642152700ec8 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in a940003f44e7e441c228151dd212642152700ec8, 671a68654a9d319d7f0d53a6321db3d9b391bdef, 4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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.

ghsa-84r8-c8cx-whp6

What to do

Upgrade Linux kernel to a940003f44e7e441c228151dd212642152700ec8, 671a68654a9d319d7f0d53a6321db3d9b391bdef or 4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 03abf2a7c65451e663b078b0ed1bfa648cd9380f, < a940003f44e7e441c228151dd212642152700ec8	Fixed in a940003f44e7e441c228151dd212642152700ec8
LinuxLinux	Affected ≥ 03abf2a7c65451e663b078b0ed1bfa648cd9380f, < 671a68654a9d319d7f0d53a6321db3d9b391bdef	Fixed in 671a68654a9d319d7f0d53a6321db3d9b391bdef
LinuxLinux	Affected ≥ 03abf2a7c65451e663b078b0ed1bfa648cd9380f, < 4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4	Fixed in 4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4
LinuxLinux	Affected =6.14	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by updating the PHY device pointer only after the last potentially failing call in phylink_bringup_phy(). Users should apply the official kernel updates that include this fix. Since this is a kernel-level vulnerability, upgrading to the patched kernel version is the recommended remediation. No additional mitigation steps are indicated in the advisory.

Description

A vulnerability in the Linux kernel's phylink component was resolved that involved improper handling of the PHY device pointer during bringup. The function phylink_bringup_phy() stored the PHY pointer before a potentially failing step, leading to stale pointers referencing freed PHY devices. This could cause subsequent operations to access invalid memory references. The issue was found in scenarios where a PHY driver arrives after switch probes, allowing a retry path that exposes this flaw. The fix involved updating the pointer only after the last failure-prone call, preventing stale references.

Impact

This vulnerability can lead to use-after-free conditions within the Linux kernel's phylink subsystem, potentially causing kernel crashes or undefined behavior when stale pointers to freed PHY devices are accessed. The impact depends on the caller context but generally risks system stability and reliability. There is no indication of remote code execution or privilege escalation from the provided data.

Summary

The Linux kernel's phylink subsystem had a vulnerability where phylink_bringup_phy() prematurely stored the PHY device pointer (pl->phydev) before a last fallible operation. On MACs implementing LPI, phy_eee_rx_clock_stop() can fail with a real MDIO error, causing callers to unwind with phy_detach() unaware of pl->phydev. This results in pl->phydev pointing to a freed phy_device, which subsequent functions like phylink_resolve() and ethtool helpers continue to access, leading to use-after-free conditions. The problem is exacerbated in the SFP path where error handling does not clear pl->phydev, leaving a dangling pointer. The vulnerability was discovered while ensuring DSA ports survive PHY drivers arriving late. The fix was to update pl->phydev only after the last call that can fail, ensuring no stale pointers remain and that PHY-side state order is preserved.

References

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