In the Linux kernel, the following vulnerability has been resolved: ACPI: CPPC: Suppress UBSAN warning caused by field…
Source GCVE Database
Not known to be exploited.
Data as of 10/25/2026, 04:40:13 UTC
No CVSS score from NVD or the CNA
- Exploitation
Not in CISA KEV, no exploitation reported
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
What to do
AI-suggested
A fix has been implemented in the Linux kernel to validate the region type and access_width before use, eliminating the UBSAN warning. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply them accordingly.
Description
In the Linux kernel, the following vulnerability has been resolved: ACPI: CPPC: Suppress UBSAN warning caused by field misuse The definition of reg->access_width changes depending on the reg->space_id type. Type ACPI_ADR_SPACE_PLATFORM_COMM uses access_width to indicate the PCC region, which can result in a UBSAN if the value is greater than 4. For example: UBSAN: shift-out-of-bounds in drivers/acpi/cppc_acpi.c:1090:9 shift exponent 32 is too large for 32-bit type 'int' CPU: 61 UID: 0 PID: 1220 Comm: (udev-worker) Not tainted 7.0.10-201.fc44.aarch64 #1 PREEMPT(lazy) Hardware name: To be filled by O.E.M. Call trace: ...(trimming) ubsan_epilogue+0x10/0x48 __ubsan_handle_shift_out_of_bounds+0xdc/0x1e0 cpc_write+0x4d0/0x670 cppc_set_perf+0x18c/0x490 cppc_cpufreq_cpu_init+0x1c8/0x380 [cppc_cpufreq] ... (trimming) Lets fix this by validating the region type, as well as whether access_width has a value. Then since we are returning bit_width directly for ACPI_ADR_SPACE_PLATFORM_COMM, drop the code correcting the size.
Impact
This vulnerability causes undefined behavior sanitizer (UBSAN) warnings due to out-of-bounds shift operations in kernel code, which may indicate a logic error or potential instability in the affected ACPI CPPC driver. There is no evidence of known exploits in the wild or direct security impact such as privilege escalation or denial of service from the provided data.
Summary
The Linux kernel contained a vulnerability in the ACPI CPPC component where the reg->access_width field was misused depending on the reg->space_id type. For the ACPI_ADR_SPACE_PLATFORM_COMM type, access_width indicates the PCC region, which could cause a UBSAN shift-out-of-bounds warning if the value exceeded 4. The fix involves validating the region type and access_width before use and removing incorrect size correction code, thus preventing the undefined behavior.
References
- nvd.nist.gov/vuln/detail/CVE-2026-64512 (opens in a new tab)
- git.kernel.org/stable/c/1b1acf2dada0cc3931bb2cb9ff8832edfbee46a1 (opens in a new tab)
- git.kernel.org/stable/c/2fb80e962029000959f651665baa4838cc92eb99 (opens in a new tab)
- git.kernel.org/stable/c/37f28bf8f14672dfa395994e41fd778a63f0bf5c (opens in a new tab)
- git.kernel.org/stable/c/b54c4632946ae42f2b39ed38abd909bbf78cbcc2 (opens in a new tab)
- git.kernel.org/stable/c/dc066bd13c860bb27d6ace511210e18b8064c1d9 (opens in a new tab)
- git.kernel.org/stable/c/e904596ba6dd108534ffa15e3e46b2fe245145e2 (opens in a new tab)
- git.kernel.org/stable/c/f29dc6132d4968e39d8fa575d1a12e2c718ce57b (opens in a new tab)