CVE-2026-28729 Overview
CVE-2026-28729 is an integer overflow vulnerability [CWE-190] in the Unified Extensible Firmware Interface (UEFI) firmware for the Intel(R) Slim Bootloader. An authenticated local adversary can trigger the flaw through active user interaction to cause information disclosure and denial of service. Successful exploitation impacts confidentiality and availability at low levels, with no impact to integrity. The issue is documented in Intel Security Advisory SA-01475.
Critical Impact
A local authenticated user can exploit an integer overflow in Slim Bootloader UEFI firmware to disclose sensitive memory contents and induce denial of service on affected platforms.
Affected Products
- Intel(R) Slim Bootloader UEFI firmware
- Platforms shipping with Intel Slim Bootloader reference firmware
- Downstream OEM builds derived from the Slim Bootloader project
Discovery Timeline
- 2026-08-11 - CVE-2026-28729 published to the National Vulnerability Database
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-28729
Vulnerability Analysis
The vulnerability resides in the UEFI firmware code path of the Intel Slim Bootloader, an open reference bootloader used to initialize Intel platforms before handing off to an operating system. An integer overflow occurs during firmware-side processing, allowing values to wrap around beyond their intended bounds. When the overflowed value is used in subsequent calculations, such as buffer sizing or offset computation, the firmware may read or expose memory that should remain protected. The consequence is information disclosure alongside a denial-of-service condition on the pre-boot environment.
Exploitation requires local access, authenticated privileges, and active user interaction, which limits opportunistic abuse. The Exploit Prediction Scoring System (EPSS) probability sits near the bottom of the distribution, and no public proof-of-concept has been observed.
Root Cause
The defect is a classic integer overflow [CWE-190]. Arithmetic on untrusted or attacker-influenced input is performed without adequate bounds validation. When the operation exceeds the maximum representable value for the underlying data type, the result wraps around and produces an unexpectedly small number. Subsequent memory operations relying on this value read past the intended boundary, exposing firmware or system memory contents to the caller.
Attack Vector
An authenticated local user interacts with a firmware interface that accepts size or length input consumed by the vulnerable code path. The attacker supplies values engineered to overflow the arithmetic, then observes returned data or triggers instability in the boot flow. Because the attack vector is local with required user interaction, remote exploitation is not applicable.
No verified exploitation code is available. Refer to Intel Security Advisory SA-01475 for vendor-supplied technical details.
Detection Methods for CVE-2026-28729
Indicators of Compromise
- Unexpected firmware error messages or platform reboots during pre-boot initialization
- Anomalous UEFI event log entries associated with Slim Bootloader stages
- Local privileged sessions preceding boot instability on affected Intel platforms
Detection Strategies
- Compare installed firmware versions against the fixed versions listed in Intel Security Advisory SA-01475 and flag hosts still running vulnerable builds
- Correlate local logon events with subsequent firmware-level errors or unplanned reboots to surface attempted exploitation
- Monitor Trusted Platform Module (TPM) Platform Configuration Register (PCR) measurements for unexpected changes across reboots
Monitoring Recommendations
- Ingest UEFI and platform telemetry into a centralized log store for retention and correlation
- Track privileged local account activity on systems running Intel Slim Bootloader firmware
- Alert on firmware version drift or downgrade attempts across the fleet
How to Mitigate CVE-2026-28729
Immediate Actions Required
- Inventory all systems running Intel Slim Bootloader-derived UEFI firmware and identify vulnerable builds
- Apply the firmware update referenced in Intel Security Advisory SA-01475 as soon as vendor images are available
- Restrict local privileged access to only administrators who require it for platform maintenance
Patch Information
Intel has published remediation guidance in Intel Security Advisory SA-01475. Platform owners should obtain updated Slim Bootloader firmware from Intel or from the OEM that integrated the bootloader into shipping products.
Workarounds
- Enforce strong authentication and least privilege on local accounts to reduce the pool of users who can reach the vulnerable interface
- Enable measured boot and Secure Boot to detect tampering with firmware components
- Disable or restrict pre-boot interfaces that expose firmware routines to unprivileged users where operationally feasible
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
