CVE-2026-99126

Kernel crash via unchecked XID error flag

Published Oct 28, 2026 · Updated Oct 28, 2026

NULL dereference in Linux s390 ctcm allows attackers to crash the kernel via XID validation errors during MPC channel setup. The mpc_validate_xid() function writes an error flag through grp->saved_xid2 even when a missing peer XID or mismatched read/write channel pairing leaves that pointer uninitialized. Reachability requires the s390 ctcm MPC driver and channel setup; public evidence does not establish the privileges or peer control needed to trigger the failure.

CVSS severityUnavailable
Unscored
EPSS probability0.18%
Next 30 days · Nov 1, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL dereference in Linux s390 ctcm allows attackers to crash the kernel via XID validation errors during MPC channel setup. The mpc_validate_xid() function writes an error flag through grp->saved_xid2 even when a missing peer XID or mismatched read/write channel pairing leaves that pointer uninitialized. Reachability requires the s390 ctcm MPC driver and channel setup; public evidence does not establish the privileges or peer control needed to trigger the failure.

The record

CVE
CVE-2026-99126
Published
Oct 28, 2026
Updated
Oct 28, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 28, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=2.6.26
  2. Affected versionversion=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <34fa3607b7604b3052b19cec8b0ad644818cdd2a
  3. Affected versionversion=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab
  4. Affected versionversion=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <b264d8422779d69febce914efc47a92a85cc382c

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.26; version=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <34fa3607b7604b3052b19cec8b0ad644818cdd2a; version=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab; version=293d984f0e3604c04dcdbf00117ddc1e5d4b1909 <b264d8422779d69febce914efc47a92a85cc382c

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)
VectorUnavailable
PrivilegesUnavailable
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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