Security readout for executives and security teams
Plain-English summary
A Linux Intel QuickI2C driver mishandles an extra byte returned by certain ACPI firmware data. This can write beyond a stack buffer and crash the kernel. The supplied CVSS score is 8.4, but exploitation requires local access and compatible Intel QuickI2C hardware and firmware behavior.
Executive priority
Treat this as a high-priority endpoint stability and kernel-memory-safety issue, not an internet-wide emergency. Accelerate assessment and routine patching for compatible Intel endpoints, especially where availability is important. There is no supplied evidence of active exploitation, and systems without the affected driver, hardware, and ACPI behavior are unlikely to be exposed.
Technical view
The intel_quicki2c driver sized ICRS and ISUB structures without accounting for a trailing ACPI _DSD byte. Copying 12 bytes into an 11-byte stack object triggers a CWE-787 out-of-bounds write. Kernel developers resolved this by adding reserved padding to the affected ACPI parameter and configuration structures.
Likely exposure
Exposure is limited to Linux systems using the affected Intel QuickI2C HID path with ACPI tables returning the documented trailing byte. The supplied version data identifies Linux 6.14, 6.16.5, and 6.17, but its range semantics are unclear; confirm exact affected and fixed builds with the distribution vendor.
Exploitation context
The bundle reports a reproducible KASAN-detected stack overwrite and kernel crash. CVSS characterizes it as local, low-complexity, requiring neither privileges nor user interaction. KEV is false, and the supplied sources provide no evidence of active exploitation or a public exploit. Confidentiality and integrity impact beyond the CVSS assessment is not demonstrated.
Researcher notes
The demonstrated primitive is a one-byte stack overwrite caused by a 12-byte copy into the 11-byte i2c_param object. The crash occurs in an asynchronous kernel worker while reading ACPI resources. Sources establish the defect and upstream fixes, but do not establish reliable code execution, affected distribution packages, or precise version-range boundaries.
Mitigation direction
- Install a vendor-supported kernel incorporating the referenced Linux stable fixes.
- Confirm the distribution's advisory maps its kernel build to either referenced fix commit.
- Prioritize compatible Intel QuickI2C endpoints showing related crashes or KASAN findings.
- If patching is delayed, consult vendor guidance for safe, supported driver-specific mitigations.
Validation and detection
- Inventory kernel versions and determine whether the intel_quicki2c driver is present or loaded.
- Check hardware and firmware inventories for systems using the affected Intel QuickI2C HID path.
- Review kernel logs for quicki2c_acpi_get_dsd_property, stack-out-of-bounds, KASAN, or unexplained boot crashes.
- Verify patched kernels contain commit 4adce86d4b13 or 1db9df89a213, as appropriate.
- After updating, confirm normal boot and QuickI2C device operation without recurring kernel errors.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-39809 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.55.9LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/4adce86d4b13d15dec7810967839b931b1598700CVE reference, Linux
- https://git.kernel.org/stable/c/1db9df89a213318a48d958385dc1b17b379dc32bCVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.