CVE-2026-42450: OpenColorIO Buffer Overflow Vulnerability

CVE-2026-42450 Overview

CVE-2026-42450 is a stack-based buffer overflow [CWE-120] in OpenColorIO, the color management framework widely used in visual effects and animation pipelines. The flaw resides in FileFormatSpi3D.cpp at line 163, where sscanf reads %s tokens from a 4096-byte line buffer into 64-byte stack destinations while parsing 3D Look-Up Table (LUT) data. A crafted .spi3d file can overflow the stack by approximately 4000 bytes on non-Windows platforms. Versions prior to 2.5.2 are affected, and the OpenColorIO maintainers fixed the issue in release 2.5.2.

Critical Impact
A malicious .spi3d LUT file can overflow stack memory by roughly 4000 bytes when opened by OpenColorIO, enabling memory corruption and potential local code execution under the user that loaded the file.

Affected Products

OpenColorIO versions prior to 2.5.2
Non-Windows platforms (Linux, macOS) processing .spi3d LUT files
Visual effects and animation applications that embed OpenColorIO as a color management dependency

Discovery Timeline

2026-06-24 - CVE-2026-42450 published to the National Vulnerability Database
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-42450

Vulnerability Analysis

The vulnerability is a classic unbounded string copy into fixed-size stack buffers. OpenColorIO's .spi3d parser reads each line of a LUT file into a 4096-byte buffer named lineBuffer. The parser then invokes sscanf with %s format specifiers to extract whitespace-delimited tokens into 64-byte stack-allocated arrays. The %s conversion specifier in sscanf has no built-in length cap, so any token longer than 63 bytes writes past the destination buffer.

Because lineBuffer accepts inputs up to 4096 bytes, an attacker can deliver a single token of nearly that length and corrupt approximately 4000 bytes of adjacent stack memory. This corruption can overwrite saved return addresses, frame pointers, and stack canaries, depending on compiler hardening. The advisory notes the issue manifests on non-Windows builds where the toolchain expands sscanf differently.

Root Cause

The root cause is missing input length validation when using sscanf("%s", buf) against an unsanitized line of attacker-controlled data. The correct pattern is to use a width-limited specifier such as %63s or to switch to a bounded parser. Mixing a large input buffer (4096 bytes) with a small output buffer (64 bytes) and an unbounded format string guarantees overflow on hostile input.

Attack Vector

Exploitation requires a victim to open or process a malicious .spi3d file with an application that uses OpenColorIO. This commonly happens in VFX, compositing, rendering, and game asset pipelines where LUT files arrive from external vendors, shared storage, or downloaded asset packs. The attack vector is local with user interaction, but the file itself can be delivered through any channel that supplies LUT assets to a workstation.

No verified proof-of-concept code has been published. The vulnerability mechanism is described in the GitHub Security Advisory GHSA-rxp3-rrgx-f547.

Detection Methods for CVE-2026-42450

Indicators of Compromise

.spi3d files containing tokens longer than 63 bytes on any single LUT data line
Crashes, segmentation faults, or stack-smashing aborts in processes linked against libOpenColorIO when loading LUT assets
Unexpected child processes or shell activity spawned from VFX, compositing, or rendering applications shortly after a LUT import

Detection Strategies

Inventory installed OpenColorIO versions across workstations and render nodes; flag any build older than 2.5.2
Scan asset repositories and shared storage for .spi3d files and inspect line lengths for anomalous tokens
Enable core dump collection on artist workstations so crashes in OpenColorIO-linked processes can be triaged for exploitation attempts

Monitoring Recommendations

Monitor process telemetry for abnormal child processes launched by DCC (Digital Content Creation) applications such as Nuke, Maya, Blender, or Houdini
Alert on stack protector failures (__stack_chk_fail) and SIGSEGV in OpenColorIO-linked binaries
Track file write and download events for .spi3d extensions sourced from untrusted networks or email

How to Mitigate CVE-2026-42450

Immediate Actions Required

Upgrade OpenColorIO to version 2.5.2 or later on every workstation, render node, and build agent
Rebuild and redistribute any in-house tools that statically link OpenColorIO against the patched release
Quarantine .spi3d files received from untrusted sources until the patch is deployed

Patch Information

The fix is included in OpenColorIO 2.5.2, published by the Academy Software Foundation. Release artifacts and source are available at the GitHub OpenColorIO Release v2.5.2. Vendors that ship OpenColorIO as a bundled dependency, including most VFX and animation suites, should pull the updated library into their next maintenance build.

Workarounds

Restrict .spi3d ingestion to a vetted internal share and block the format at email and web gateways
Run color-pipeline tools under a least-privileged user account to limit the blast radius of a successful exploit
Validate LUT files with a pre-processing script that rejects any line containing a token longer than 63 characters before they reach OpenColorIO

bash

# Reject .spi3d files with overlong tokens before they reach OpenColorIO
awk '{ for (i=1; i<=NF; i++) if (length($i) > 63) { print FILENAME": overlong token"; exit 1 } }' suspicious.spi3d