VulnerabilityPublished 25 Jul 2026Updated 6 Nov 2026

CVE-2026-64369: Linux kernel · s390: Revert support for DCACHE_WORD_ACCESS

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in c94806905e02cc8e17a69c822d93c41743b7ffc5 : update Linux kernel when convenient.

Data as of 6 Nov 2026, 17:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

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: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in c94806905e02cc8e17a69c822d93c41743b7ffc5, c9e0f1517631ac08987f8385817119bccf2f1f12, be79d285bea70d0edd5015bd487311bfa8cbebc9 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 6 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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.

What to do

Upgrade Linux kernel to c94806905e02cc8e17a69c822d93c41743b7ffc5, c9e0f1517631ac08987f8385817119bccf2f1f12, be79d285bea70d0edd5015bd487311bfa8cbebc9 or 37540b8c287fc817bdbd0c62bb75ad6eab0e5d03.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 802ba53eefc592a6a82231f74e19bafe3256f172, < c94806905e02cc8e17a69c822d93c41743b7ffc5	Fixed in c94806905e02cc8e17a69c822d93c41743b7ffc5
LinuxLinux	Affected ≥ 802ba53eefc592a6a82231f74e19bafe3256f172, < c9e0f1517631ac08987f8385817119bccf2f1f12	Fixed in c9e0f1517631ac08987f8385817119bccf2f1f12
LinuxLinux	Affected ≥ 802ba53eefc592a6a82231f74e19bafe3256f172, < be79d285bea70d0edd5015bd487311bfa8cbebc9	Fixed in be79d285bea70d0edd5015bd487311bfa8cbebc9
LinuxLinux	Affected ≥ 802ba53eefc592a6a82231f74e19bafe3256f172, < 37540b8c287fc817bdbd0c62bb75ad6eab0e5d03	Fixed in 37540b8c287fc817bdbd0c62bb75ad6eab0e5d03
LinuxLinux	Affected =6.7	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: s390: Revert support for DCACHE_WORD_ACCESS load_unaligned_zeropad() reads eight bytes from unaligned addresses and may cross page boundaries. It handles exceptions which may happen if reading from the second page results in an exception. For pages which are donated to the Ultravisor for secure execution purposes the do_secure_storage_access() exception handler however does not handle such exceptions correctly. Such an exception may result in an endless exception loop which will never be resolved. An attempt to fix this [1] turned out to be not sufficient. For now revert load_unaligned_zeropad() until this problem has been resolved in a proper way. Note that the implementation of load_unaligned_zeropad() itself is correct. The revert is just a temporary workaround until there is complete fix for secure storage access exceptions. [1] commit b00be77302d7 ("s390/mm: Add missing secure storage access fixups for donated memory")

References

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