CVE-2026-64004

Kernel crash via unlocked AF_IUCV socket race

Published Jul 19, 2026 · Updated Jul 19, 2026

Race condition in affected Linux Kernel releases allows local users to crash the kernel through concurrent AF_IUCV HIPER socket calls. The SO_MSGSIZE branch in iucv_sock_getsockopt() reads iucv->hs_dev->mtu without the socket lock after racing recvmsg() closes the socket and clears hs_dev. An unprivileged user with an AF_IUCV HIPER socket on s390 controls both sides of the race, causing an oops or panic and exposing a use-after-free read.

CVSS severity7.8
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in affected Linux Kernel releases allows local users to crash the kernel through concurrent AF_IUCV HIPER socket calls. The SO_MSGSIZE branch in iucv_sock_getsockopt() reads iucv->hs_dev->mtu without the socket lock after racing recvmsg() closes the socket and clears hs_dev. An unprivileged user with an AF_IUCV HIPER socket on s390 controls both sides of the race, causing an oops or panic and exposing a use-after-free read.

The record

CVE
CVE-2026-64004
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 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=3.4
  2. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <1fc30bd4e55e2dd622d2d366cecd732c1841bbee
  3. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <3589d20a666caf30ad100c960a2de7de390fce88
  4. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <45bb8de8c95d8899f4b8f61bd9bceb8132af73cb
  5. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <69554adc7a6fa04ede3ad7512321d83748e3c920
  6. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <6e792b8dd3002bbc4136745928a9605df1a72b8a
  7. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <884eb247b74d86db97e3a37f0d6fc8e1e83590dd
  8. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <9817369243380e287ebe5525411557eaa3aa2a79
  9. Affected versionversion=51363b8751a673a00ad48eea895266396d53fa52 <cd691beafea0dd779e69e81ccc26b0ab50efcb5e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.4; version=51363b8751a673a00ad48eea895266396d53fa52 <1fc30bd4e55e2dd622d2d366cecd732c1841bbee; version=51363b8751a673a00ad48eea895266396d53fa52 <3589d20a666caf30ad100c960a2de7de390fce88; version=51363b8751a673a00ad48eea895266396d53fa52 <45bb8de8c95d8899f4b8f61bd9bceb8132af73cb; version=51363b8751a673a00ad48eea895266396d53fa52 <69554adc7a6fa04ede3ad7512321d83748e3c920; version=51363b8751a673a00ad48eea895266396d53fa52 <6e792b8dd3002bbc4136745928a9605df1a72b8a; version=51363b8751a673a00ad48eea895266396d53fa52 <884eb247b74d86db97e3a37f0d6fc8e1e83590dd; version=51363b8751a673a00ad48eea895266396d53fa52 <9817369243380e287ebe5525411557eaa3aa2a79; version=51363b8751a673a00ad48eea895266396d53fa52 <cd691beafea0dd779e69e81ccc26b0ab50efcb5e

Published CVSS scores

7.8Linux Kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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

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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