CVE-2025-3407: Nothings Stb Image.h RCE Vulnerability

CVE-2025-3407 Overview

A critical out-of-bounds read vulnerability has been identified in the Nothings stb library, specifically affecting the stbhw_build_tileset_from_image function. This vulnerability allows remote attackers to manipulate the h_count and v_count arguments to trigger an out-of-bounds read condition. The stb library is a widely-used collection of single-file public domain libraries for C/C++, commonly embedded in game engines, image processing tools, and various multimedia applications.

Critical Impact

Remote attackers can exploit this out-of-bounds read vulnerability to potentially leak sensitive memory contents, crash applications, or use the information disclosure as a stepping stone for further exploitation.

Affected Products

• nothings stb_image.h (all versions up to commit f056911)

Discovery Timeline

• 2025-04-08 - CVE CVE-2025-3407 published to NVD
• 2025-10-16 - Last updated in NVD database

Technical Details for CVE-2025-3407

Vulnerability Analysis

This vulnerability is an out-of-bounds read (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) affecting the stbhw_build_tileset_from_image function in the stb header-only library collection. The function processes tileset images for the herringbone wang tile generator component.

When processing image data, the function accepts h_count (horizontal count) and v_count (vertical count) parameters that specify the dimensions of the tileset grid. These parameters are used to calculate memory offsets when reading pixel data from the source image. However, insufficient validation of these input values allows attackers to supply malformed parameters that cause the function to read beyond the allocated buffer boundaries.

The stb library follows a rolling release model without formal versioning, which complicates version tracking for affected deployments. The vendor was contacted about this vulnerability but did not respond, leaving users without an official patch timeline.

Root Cause

The root cause of this vulnerability lies in insufficient boundary validation for the h_count and v_count parameters within the stbhw_build_tileset_from_image function. When these values are manipulated to exceed expected bounds, the function performs memory read operations outside the allocated image buffer, leading to an out-of-bounds read condition. This is a classic example of improper input validation combined with unsafe memory access patterns common in C-based image processing code.

Attack Vector

This vulnerability can be exploited remotely by delivering a specially crafted image file to an application that uses the vulnerable stb library function. The attack requires user interaction—a victim must open or process the malicious image file. The attacker manipulates the image metadata or structure to cause invalid h_count and v_count values to be passed to the vulnerable function.

When the malicious image is processed, the out-of-bounds read occurs, potentially exposing sensitive memory contents. In some scenarios, this information disclosure could reveal memory layout information useful for bypassing ASLR, or the read could trigger a crash if it accesses unmapped memory regions.

The vulnerability mechanism centers on the tileset parsing logic where image dimensions are used to calculate buffer offsets. Without proper bounds checking, an attacker-controlled image can specify dimensions that cause reads beyond the image buffer. For detailed technical information, see the VulDB advisory.

Detection Methods for CVE-2025-3407

Indicators of Compromise

• Unexpected application crashes during image processing operations, particularly when handling tileset or wang tile images
• Memory access violations or segmentation faults in processes using stb library components
• Unusual memory read patterns detected by memory sanitizers (ASan, MSan) in applications using stbhw_build_tileset_from_image

Detection Strategies

• Deploy SentinelOne Singularity endpoint protection to detect anomalous memory access patterns and potential exploitation attempts
• Implement runtime memory protection tools such as AddressSanitizer (ASan) in development and testing environments to catch out-of-bounds reads
• Monitor application logs for crashes or errors originating from stb library functions, particularly herringbone wang tile processing components

Monitoring Recommendations

• Enable crash dump analysis for applications using stb libraries to identify exploitation attempts
• Implement file integrity monitoring for image files being processed by vulnerable applications
• Use SentinelOne's behavioral AI to detect post-exploitation activities that may follow information disclosure

How to Mitigate CVE-2025-3407

Immediate Actions Required

• Audit all applications and dependencies for usage of the stb library, particularly the stbhw_build_tileset_from_image function
• Update to the latest commit of the stb repository if available, though no official patch has been confirmed
• Implement input validation at the application level before passing image data to stb library functions
• Consider sandboxing or isolating image processing operations to limit the impact of potential exploitation

Patch Information

The stb library uses a rolling release model without formal versioning. The vendor (Nothings) was contacted about this disclosure but did not respond. Users should monitor the stb GitHub repository for any commits addressing this vulnerability. The affected code is present up to commit f056911. Until an official fix is available, implementing application-level mitigations is strongly recommended.

Workarounds

• Validate all image dimensions and tileset parameters before passing them to stbhw_build_tileset_from_image
• Implement maximum bounds checking for h_count and v_count parameters at the application level
• Use memory-safe wrappers or alternative image processing libraries for critical applications
• Deploy SentinelOne Singularity for runtime protection against memory corruption exploitation

# Example: Compile with AddressSanitizer to detect out-of-bounds reads
gcc -fsanitize=address -g -o image_processor image_processor.c

# Example: Run with ASan to catch memory issues during testing
ASAN_OPTIONS=detect_oob_access=1 ./image_processor input_image.png