UBSAN warning via PCC region-number shift misuse
Published Jul 25, 2026 · Updated Jul 25, 2026
Undefined behavior in Linux Kernel allows attackers to trigger an out-of-bounds shift during ACPI CPPC performance initialization. In drivers/acpi/cppc_acpi.c, cpc_write shifts by reg->access_width times eight even though PLATFORM_COMM uses that field as a PCC region number. The demonstrated condition requires a UBSAN-instrumented kernel and a PLATFORM_COMM register with access_width above 4; no attacker-controlled route or service interruption is documented.
Summary
What happened
Undefined behavior in Linux Kernel allows attackers to trigger an out-of-bounds shift during ACPI CPPC performance initialization. In drivers/acpi/cppc_acpi.c, cpc_write shifts by reg->access_width times eight even though PLATFORM_COMM uses that field as a PCC region number. The demonstrated condition requires a UBSAN-instrumented kernel and a PLATFORM_COMM register with access_width above 4; no attacker-controlled route or service interruption is documented.
The record
- CVE
- CVE-2026-64512
- Published
- Jul 25, 2026
- Updated
- Jul 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jul 25, 2026CVE publishedPublication date reported by the CVE source.
- Jul 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=01fc53be672acae37e611c80cc0b4f3939584de3 <e904596ba6dd108534ffa15e3e46b2fe245145e2
- Affected versionversion=1b890ae474d19800a6be1696df7fb4d9a41676e4 <2fb80e962029000959f651665baa4838cc92eb99
- Affected versionversion=2f4a4d63a193be6fd530d180bb13c3592052904c <1b1acf2dada0cc3931bb2cb9ff8832edfbee46a1
- Affected versionversion=2f4a4d63a193be6fd530d180bb13c3592052904c <37f28bf8f14672dfa395994e41fd778a63f0bf5c
- Affected versionversion=2f4a4d63a193be6fd530d180bb13c3592052904c <dc066bd13c860bb27d6ace511210e18b8064c1d9
- Affected versionversion=2f4a4d63a193be6fd530d180bb13c3592052904c <f29dc6132d4968e39d8fa575d1a12e2c718ce57b
- Affected versionversion=4949affd5288b867cdf115f5b08d6166b2027f87 <b54c4632946ae42f2b39ed38abd909bbf78cbcc2
- Affected versionversion=5.15.154 <5.15.155
- Affected versionversion=6.1.90 <6.1.178
- Affected versionversion=6.6.30 <6.6.145
- Affected versionversion=6.8.9 <6.9
- Affected versionversion=6.9
- Affected versionversion=6cb6b12b78dcd8867a3fdbb1b6d0ed1df2b208d1
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo