CVE-2026-45889

Kernel crash via MPTCP receive-buffer race

Published May 27, 2026 · Updated May 27, 2026

Divide-by-zero in Linux Kernel 6.18 before 6.18.14 and 6.19 before 6.19.4 allows local users to crash the kernel via MPTCP. mptcp_rcvbuf_grow() counts MPTCP-level out-of-order data while rcvspace initialization can finish in a receive callback, leaving the growth divisor at zero. Triggering the Oops requires an active MPTCP socket, concurrent subflows with out-of-order data, and user space holding the socket-level lock.

CVSS severity5.5
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero in Linux Kernel 6.18 before 6.18.14 and 6.19 before 6.19.4 allows local users to crash the kernel via MPTCP. mptcp_rcvbuf_grow() counts MPTCP-level out-of-order data while rcvspace initialization can finish in a receive callback, leaving the growth divisor at zero. Triggering the Oops requires an active MPTCP socket, concurrent subflows with out-of-order data, and user space holding the socket-level lock.

The record

CVE
CVE-2026-45889
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-369, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.18
  2. Affected versionversion=e118cdc34dd109562b64f6a397f68cd33b041d5b <400ee4854adef1e4983812a3decf6717ea020136
  3. Affected versionversion=e118cdc34dd109562b64f6a397f68cd33b041d5b <6b329393502e5857662b851a13f947209c588587
  4. Affected versionversion=e118cdc34dd109562b64f6a397f68cd33b041d5b <fb7bf00b04a6b48859f52035d4e745848c2b4c79

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.18; version=e118cdc34dd109562b64f6a397f68cd33b041d5b <400ee4854adef1e4983812a3decf6717ea020136; version=e118cdc34dd109562b64f6a397f68cd33b041d5b <6b329393502e5857662b851a13f947209c588587; version=e118cdc34dd109562b64f6a397f68cd33b041d5b <fb7bf00b04a6b48859f52035d4e745848c2b4c79

Published CVSS scores

5.7Canonical UbuntuCVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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