VulnerabilityPublished 18 Oct 2026

CVE-2026-98788: Linux kernel · futex: Fix private hash use-after-free on resize

Affects Linux kernelSource CVE Database V5

Not known to be exploited : upgrade to f35e3b5784221654f9cdbd6222275a7fa203f6c3 or 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af soon.

Data as of 26 Oct 2026, 14:05 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f35e3b5784221654f9cdbd6222275a7fa203f6c3, 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af

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 f35e3b5784221654f9cdbd6222275a7fa203f6c3 or 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 56180dd20c19e5b0fa34822997a9ac66b517e7b3, < f35e3b5784221654f9cdbd6222275a7fa203f6c3	Fixed in f35e3b5784221654f9cdbd6222275a7fa203f6c3
LinuxLinux	Affected ≥ 56180dd20c19e5b0fa34822997a9ac66b517e7b3, < 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af	Fixed in 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af
LinuxLinux	Affected =6.17	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 f35e3b5784221654f9cdbd6222275a7fa203f6c3 and 5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af. No additional mitigation actions are required beyond applying the official patch.

Description

A use-after-free vulnerability in the Linux kernel's futex private hash resizing mechanism was fixed. The issue involved improper ordering of assignments leading to a race condition where a reader could access a freed hash. The fix changes the order of assignments to ensure safe synchronization without relying on scoped RCU guards.

Impact

The vulnerability could lead to use-after-free conditions in the futex subsystem of the Linux kernel, potentially causing kernel crashes or undefined behavior. No known exploits in the wild have been reported. The impact is limited to affected kernel versions and requires conditions that trigger the resizing of the futex private hash.

Summary

CVE-2026-98788 addresses a use-after-free vulnerability in the Linux kernel's futex subsystem. The flaw arises during resizing of the private hash where the assignment of mmph->batches and mmph->hash occurs in an unsafe order. Specifically, mmph->batches was set before mmph->hash under an RCU scoped guard, but this did not prevent new grace periods from starting between these assignments. As a result, futex_ref_drop() could advance while a reader still held a pointer to the old hash, causing use-after-free. The patch fixes this by assigning mmph->hash before mmph->batches and removing the unnecessary scoped RCU guard, ensuring proper synchronization and preventing the use-after-free condition.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:57 UTC

Technical details

References

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