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Review reviewHigh

CVE-2026-64004

Linux

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.

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

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.

Affected product and versions

Product
Linux
Affected versions
>= 51363b8751a673a00ad48eea895266396d53fa52 < 884eb247b74d86db97e3a37f0d6fc8e1e83590dd, >= 51363b8751a673a00ad48eea895266396d53fa52 < 45bb8de8c95d8899f4b8f61bd9bceb8132af73cb, >= 51363b8751a673a00ad48eea895266396d53fa52 < 1fc30bd4e55e2dd622d2d366cecd732c1841bbee, >= 51363b8751a673a00ad48eea895266396d53fa52 < cd691beafea0dd779e69e81ccc26b0ab50efcb5e, >= 51363b8751a673a00ad48eea895266396d53fa52 < 6e792b8dd3002bbc4136745928a9605df1a72b8a, >= 51363b8751a673a00ad48eea895266396d53fa52 < 9817369243380e287ebe5525411557eaa3aa2a79, >= 51363b8751a673a00ad48eea895266396d53fa52 < 69554adc7a6fa04ede3ad7512321d83748e3c920, >= 51363b8751a673a00ad48eea895266396d53fa52 < 3589d20a666caf30ad100c960a2de7de390fce88, >= 3.4
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available