CVE-2025-3406 Overview
CVE-2025-3406 is an out-of-bounds read vulnerability in Nothings stb, a widely used collection of single-file public domain libraries for C/C++. The flaw resides in the stbhw_build_tileset_from_image function within the Header Array Handler component. Attackers can trigger the condition by manipulating the w argument, causing the library to read memory beyond allocated buffer boundaries. The vulnerability is remotely exploitable but requires user interaction. Nothings distributes stb through a rolling release model, so no discrete affected or fixed version identifiers exist. According to the disclosure, the vendor was contacted early but did not respond.
Critical Impact
Remote attackers can trigger an out-of-bounds read in applications embedding vulnerable stb code, potentially disclosing adjacent memory contents or causing process crashes.
Affected Products
- Nothings stb_image.h (rolling release, up to commit f056911)
- Applications statically linking the vulnerable stb header
- Downstream projects consuming affected versions of the stbhw tileset builder
Discovery Timeline
- 2025-04-08 - CVE-2025-3406 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3406
Vulnerability Analysis
The vulnerability is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and manifests as an out-of-bounds read. The defect lives inside stbhw_build_tileset_from_image, a routine in the stb_herringbone_wang_tile component that constructs a tileset from an input image. Passing a crafted w (width) argument causes the function to compute indices that exceed the bounds of the header array, prompting reads from unintended memory regions.
Because stb libraries are shipped as single-file headers, the vulnerable code is compiled directly into any application that includes it. This broadens the exposure surface across image-processing tools, game engines, and content pipelines that rely on the stbhw tileset functionality.
Root Cause
The root cause is missing or insufficient validation of the w parameter passed to stbhw_build_tileset_from_image. The function trusts the caller-supplied width when computing offsets into the header array without verifying that the resulting index remains within the allocated buffer. When an attacker controls the input image or its metadata, the miscalculated offset dereferences memory outside the intended region.
Attack Vector
Exploitation requires an attacker to supply a crafted image or tileset input to an application built with vulnerable stb code. User interaction is required, typically opening or processing the malicious file. Successful exploitation leaks limited memory contents or triggers a denial-of-service condition through process termination. The vulnerability does not by itself provide code execution, but memory disclosure can aid follow-on attacks against protections such as address space layout randomization.
No verified proof-of-concept code has been published. See the VulDB entry for additional technical details.
Detection Methods for CVE-2025-3406
Indicators of Compromise
- Unexpected crashes or segmentation faults in processes that parse tileset or image inputs using stb_herringbone_wang_tile
- Anomalous memory read patterns in applications embedding stb_image.h when handling untrusted files
- Malformed image files with abnormal width fields delivered through email, uploads, or shared repositories
Detection Strategies
- Audit software builds and dependencies to identify applications that statically include vulnerable versions of stb headers up to commit f056911.
- Deploy fuzzing harnesses against stbhw_build_tileset_from_image using AddressSanitizer to surface out-of-bounds reads during development.
- Monitor endpoint telemetry for repeated crashes in image-processing binaries following the arrival of external files.
Monitoring Recommendations
- Enable AddressSanitizer or MemorySanitizer in test and staging builds to catch boundary violations before production deployment.
- Forward application crash telemetry and Windows Error Reporting or Linux core dumps to a central analytics platform for correlation.
- Track file-parsing services for repeated failures tied to specific user-supplied images or tileset assets.
How to Mitigate CVE-2025-3406
Immediate Actions Required
- Inventory all software that vendors or embeds stb headers, particularly stb_image.h and the herringbone Wang tile module.
- Restrict processing of untrusted tileset or image inputs in applications known to link vulnerable stb code.
- Isolate image-processing workloads in sandboxed or containerized environments to limit blast radius from memory disclosure.
Patch Information
Nothings distributes stb as a rolling release, so no discrete patched version number is published. Maintainers and downstream consumers should track the upstream stb repository for commits addressing the stbhw_build_tileset_from_image boundary check and rebuild affected binaries once a fix lands. Reference the VulDB advisory and the VulDB submission record for tracking.
Workarounds
- Disable or remove code paths that invoke stbhw_build_tileset_from_image when handling attacker-controlled inputs.
- Validate and clamp the w argument in caller code to a maximum value derived from actual buffer allocations before invoking the function.
- Pre-process images through a hardened parser to reject inputs with anomalous dimensions before passing them to stb.
# Configuration example: rebuild with AddressSanitizer to catch OOB reads
CFLAGS="-fsanitize=address -fno-omit-frame-pointer -g" \
LDFLAGS="-fsanitize=address" \
make clean all
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
