VulnerabilityPublished 18 Oct 2026

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

Affects Linux kernelSource CVE Database V5

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 Medium by Threat Radar's AI analysis · 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.

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

This issue is fixed in the Linux kernel by commits identified as a940003f44e7e441c228151dd212642152700ec8, 671a68654a9d319d7f0d53a6321db3d9b391bdef, and 4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4. Users should update to a patched kernel version that includes these fixes. No additional mitigation is required as the fix prevents stale pointer usage by changing the pointer assignment order.

Description

A vulnerability in the Linux kernel's phylink subsystem was fixed by ensuring the PHY device pointer is recorded only after the last potentially failing step during bringup. Previously, an error during PHY initialization could leave a stale pointer to a freed PHY device, causing subsequent operations to access invalid memory. This issue affected Linux kernel version 6.14 and was resolved by changing the order of pointer assignment to prevent use-after-free conditions.

Impact

The vulnerability could cause use-after-free conditions in the kernel's phylink subsystem, potentially leading to kernel crashes or undefined behavior when accessing freed PHY device pointers. The impact depends on how the PHY connection failure is handled but may cause instability in network device management. There is no indication of remote exploitation or privilege escalation from the provided data.

Summary

The Linux kernel's phylink_bringup_phy() function stored the PHY device pointer (pl->phydev) before completing the last fallible operation. If phy_eee_rx_clock_stop() failed due to an MDIO error, the callers would unwind with phy_detach(), which does not clear pl->phydev. This left pl->phydev pointing to a freed phy_device, leading to use-after-free when phylink_resolve() and ethtool helpers accessed it. The problem was exacerbated in certain paths like the SFP path, where pl->phydev was not cleared after failure, causing persistent stale pointers. The fix involved publishing the PHY pointer only after the last call that can fail, ensuring no stale pointers remain and preventing invalid memory access.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:38 UTC

Technical details

References

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