CVE-2026-37540 Overview
CVE-2026-37540 is an integer overflow vulnerability [CWE-190] in the OpenAMP v2025.10.0 ELF loader. The flaw resides in elf_loader.c, where the loader multiplies two attacker-controlled 16-bit values from the ELF header without overflow checking. On 32-bit embedded platforms such as STM32MP1, Zynq, and i.MX, the multiplication can wrap to a small value and undermine downstream allocation or bounds logic during firmware image parsing.
Critical Impact
A local attacker who supplies a crafted firmware image to the remoteproc subsystem can trigger memory corruption leading to loss of confidentiality, integrity, and availability on the affected embedded system.
Affected Products
- OpenAMP v2025.10.0 (ELF loader component, lib/remoteproc/elf_loader.c)
- 32-bit embedded platforms using OpenAMP remoteproc (STM32MP1, Zynq, i.MX)
- Downstream firmware projects bundling the affected OpenAMP release
Discovery Timeline
- 2026-05-01 - CVE-2026-37540 published to NVD
- 2026-05-07 - Last updated in NVD database
Technical Details for CVE-2026-37540
Vulnerability Analysis
OpenAMP's ELF loader parses firmware images destined for a remote processor. During parsing, the loader reads two 16-bit fields from the ELF header (typically program/section header count and entry size) and multiplies them to compute a buffer size. The product is stored in a 32-bit integer without prior validation.
When both operands approach their 16-bit maximum, the resulting 32-bit value can wrap. The loader then allocates an undersized buffer while subsequent parsing logic uses the original, unbounded counts to iterate. This mismatch produces an out-of-bounds write during firmware image processing.
Because OpenAMP runs on Asymmetric Multi-Processing (AMP) systems coordinating between a Cortex-A host and a Cortex-M coprocessor, exploitation can corrupt remoteproc state controlling the secondary core.
Root Cause
The root cause is missing arithmetic bounds checking in elf_loader.c before multiplying two attacker-controlled uint16_t header fields. The code path assumes header values are well-formed and does not validate the product against SIZE_MAX or the available buffer size. This pattern matches CWE-190 (Integer Overflow or Wraparound).
Attack Vector
Exploitation requires local access to submit a malicious ELF firmware image to the remoteproc loader. The attacker crafts ELF header fields whose product overflows 32-bit arithmetic. When the loader parses the image, the truncated allocation size leads to memory corruption during section copy. No authentication or user interaction is required beyond the ability to provide the firmware blob to the loading path.
The vulnerability mechanism is described in the OpenAMP ELF Loader Source and a GitHub Gist Code Snippet. No verified public exploit is available.
Detection Methods for CVE-2026-37540
Indicators of Compromise
- ELF firmware images with abnormally large e_phnum, e_shnum, e_phentsize, or e_shentsize fields whose products exceed UINT32_MAX.
- Unexpected remoteproc load failures, kernel log entries, or coprocessor crashes following firmware load attempts.
- Modified or unsigned firmware blobs staged in /lib/firmware or equivalent paths on embedded Linux hosts.
Detection Strategies
- Static analysis of firmware images before deployment to flag ELF headers with arithmetic that overflows when multiplied.
- Runtime instrumentation of elf_loader.c paths with overflow-checked arithmetic builtins such as __builtin_mul_overflow.
- File integrity monitoring on firmware directories to detect unauthorized image substitution.
Monitoring Recommendations
- Log all rproc_boot and remoteproc load events with the SHA-256 hash of the loaded image.
- Alert on coprocessor reset loops or repeated remoteproc state transitions correlated with firmware updates.
- Centralize embedded device telemetry to detect anomalous firmware loads across fleets.
How to Mitigate CVE-2026-37540
Immediate Actions Required
- Inventory all builds that link against OpenAMP v2025.10.0 and identify 32-bit targets running remoteproc.
- Restrict the ability to write to firmware load paths to privileged accounts only.
- Enforce signed firmware verification before passing images to the OpenAMP ELF loader.
Patch Information
No vendor patch advisory was referenced in the NVD entry at publication. Track the upstream OpenAMP GitHub Repository for fixes to lib/remoteproc/elf_loader.c that introduce overflow-checked multiplication and validate ELF header field products against allocation limits.
Workarounds
- Apply a local patch that uses __builtin_mul_overflow to validate the product of ELF header counts and entry sizes before allocation.
- Reject ELF images whose e_phnum * e_phentsize or e_shnum * e_shentsize exceeds the firmware buffer size.
- Where feasible, rebuild affected firmware on 64-bit toolchains or constrain remoteproc to load only vendor-signed images from read-only storage.
# Configuration example: enforce signed firmware and read-only firmware path
mount -o remount,ro /lib/firmware
chmod 0500 /lib/firmware
chown root:root /lib/firmware
# Require kernel module signature enforcement on remoteproc loads
echo 1 > /sys/module/firmware_class/parameters/path_check
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
