VulnerabilityPublished 28 Oct 2026

CVE-2026-99126: Linux kernel · s390/ctcm: Prevent XID null dereference

Source GCVE Database

Authoritative record:CVE-2026-99126

Not known to be exploited · fixed in b264d8422779d69febce914efc47a92a85cc382c : update Linux kernel when convenient.

Data as of 28 Oct 2026, 14:12 UTC

Severity

Medium

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

Patch: Available – fixed in b264d8422779d69febce914efc47a92a85cc382c, 34fa3607b7604b3052b19cec8b0ad644818cdd2a, 8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab

Exploitation evidence

Disclosed: evidence found.
CVE published 28 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.

ghsa-pcv7-392q-p29w

What to do

Upgrade Linux kernel to b264d8422779d69febce914efc47a92a85cc382c, 34fa3607b7604b3052b19cec8b0ad644818cdd2a or 8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 293d984f0e3604c04dcdbf00117ddc1e5d4b1909, < b264d8422779d69febce914efc47a92a85cc382c	Fixed in b264d8422779d69febce914efc47a92a85cc382c
LinuxLinux	Affected ≥ 293d984f0e3604c04dcdbf00117ddc1e5d4b1909, < 34fa3607b7604b3052b19cec8b0ad644818cdd2a	Fixed in 34fa3607b7604b3052b19cec8b0ad644818cdd2a
LinuxLinux	Affected ≥ 293d984f0e3604c04dcdbf00117ddc1e5d4b1909, < 8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab	Fixed in 8a2f7a4ad1d81612fa65bfa4d392ba1bb2f5eeab
LinuxLinux	Affected =2.6.26	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by changing the pointer usage in the mpc_validate_xid() function. Users should apply the official kernel update that includes this fix once available. No other mitigation steps are indicated.

Description

A null pointer dereference vulnerability was identified and fixed in the Linux kernel's s390/ctcm subsystem. The issue occurs when the mpc_validate_xid() function attempts to set a flag on a NULL pointer due to uninitialized grp->saved_xid2 in certain error conditions. The fix replaces the problematic pointer with a guaranteed valid one to prevent the null dereference.

References

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