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VulnerabilityPublished Updated

CVE-2026-64004: Linux kernel · net/iucv: fix locking in .getsockopt

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in cd691beafea0dd779e69e81ccc26b0ab50efcb5e : patch Linux kernel soon.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in cd691beafea0dd779e69e81ccc26b0ab50efcb5e, 9817369243380e287ebe5525411557eaa3aa2a79, 69554adc7a6fa04ede3ad7512321d83748e3c920 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < cd691beafea0dd779e69e81ccc26b0ab50efcb5e
Fixed in
  • cd691beafea0dd779e69e81ccc26b0ab50efcb5e
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < 9817369243380e287ebe5525411557eaa3aa2a79
Fixed in
  • 9817369243380e287ebe5525411557eaa3aa2a79
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < 69554adc7a6fa04ede3ad7512321d83748e3c920
Fixed in
  • 69554adc7a6fa04ede3ad7512321d83748e3c920
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < 3589d20a666caf30ad100c960a2de7de390fce88
Fixed in
  • 3589d20a666caf30ad100c960a2de7de390fce88
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < 884eb247b74d86db97e3a37f0d6fc8e1e83590dd
Fixed in
  • 884eb247b74d86db97e3a37f0d6fc8e1e83590dd
LinuxLinuxAffected
  • ≥ 51363b8751a673a00ad48eea895266396d53fa52, < 45bb8de8c95d8899f4b8f61bd9bceb8132af73cb
Fixed in
  • 45bb8de8c95d8899f4b8f61bd9bceb8132af73cb

Description

In the Linux kernel, the following vulnerability has been resolved: net/iucv: fix locking in .getsockopt Mirror iucv_sock_setsockopt() and wrap the whole switch in lock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock becomes redundant and is removed. Any AF_IUCV HIPER user can potentially crash the kernel by racing recvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences iucv->hs_dev->mtu after iucv_sock_close() (called from the racing recvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference oops.

References

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