CVE-2026-99133

Socket disconnection via unchecked transport window updates

Published Oct 28, 2026 · Updated Oct 28, 2026

Incorrect window updates in Linux AF_IUCV allow local users to disconnect their own sockets through crafted recvmsg operations. iucv_sock_recvmsg() sends HiperSockets-only control messages on classic z/VM sockets and allocates sleeping memory under a spinlock, while non-atomic msg_recv accounting permits duplicate receive credits. The disconnect requires an unprivileged process to set SO_MSGLIMIT to 1 on its own socket on an S390 system with AF_IUCV support; a kernel crash is not established.

CVSS severityUnavailable

Unscored

EPSS probability0.18%

Next 30 days · Nov 1, 2026

Known exploitationUnconfirmed

Based on sourced intelligence

Hinoki checkNot available

Coverage for this vulnerability

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Summary

What happened

The record

CVE: CVE-2026-99133
Published: Oct 28, 2026
Updated: Oct 28, 2026

Vendor: The Linux Kernel Organization
Product: Linux
Classifications: Unavailable

Attack vector: local
Privileges: authenticated

Timeline

How it unfolded

Oct 28, 2026CVE publishedPublication date reported by the CVE source.
Oct 28, 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.

Affected versionversion=3.2
Affected versionversion=3881ac441f642d56503818123446f7298442236b <8f2efa742f4cfe7dd756154f8bc07350dbe3ec92
Affected versionversion=3881ac441f642d56503818123446f7298442236b <fa5acd038ea657ad5033713d6916214cbd349151
Affected versionversion=3881ac441f642d56503818123446f7298442236b <fe7393a627db2d093e8c0cae69d619b30fefae5f

What conditions does exploitation require?

Attack vectorlocal

Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.2; version=3881ac441f642d56503818123446f7298442236b <8f2efa742f4cfe7dd756154f8bc07350dbe3ec92; version=3881ac441f642d56503818123446f7298442236b <fa5acd038ea657ad5033713d6916214cbd349151; version=3881ac441f642d56503818123446f7298442236b <fe7393a627db2d093e8c0cae69d619b30fefae5f

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026

Latest reporting daySep 28, 2026

Latest daily unique IPsUnavailable

Prior 30-day averageUnavailable

SourceShadowserver honeypots (KEV)

Vectorlocal

Privilegesauthenticated

Known exploitationUnconfirmed

Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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