OpenImageIO EUVD-2026-83137

Exploitation requires that OpenImageIO (prior to 3.0.21.0 / 3.1.16.0 / 3.2.0.3-beta1) be used to WRITE GIF output while reading a maliciously crafted, TRUNCATED TGA input - the specific trigger is a truncated TGA that leaves a pending GIF frame processed during GIFOutput close, combined with image dimensions large enough to overflow the signed 32-bit numPixels × (splitElt−firstElt) product in GifSplitPalette(). Limiting factors: the vector is LOCAL (AV:L) with required user interaction (UI:R) - a user or automated job must invoke the TGA→GIF conversion path; there is no unauthenticated remote trigger, no privilege escalation, and no attacker code execution. Realistic exposure is confined to services or workflows that transcode untrusted images to GIF using OpenImageIO.

This is a genuine but low-priority defensive-hardening issue, not an urgent threat. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H, base 5.5) describes a pure availability impact - a process crash - with no confidentiality or integrity loss. The attack is LOCAL (AV:L) and requires user interaction (UI:R): a victim must run an OpenImageIO-based tool that converts a maliciously crafted/truncated TGA into GIF output. There is no remote network exposure and no code execution: the integer overflow in GifSplitPalette() drives an out-of-bounds READ (CWE-125), which in practice terminates the process rather than yielding attacker control. No EPSS score, no CISA KEV listing, and no public proof-of-concept exploit were provided, consistent with a batch of GitHub-advisory-sourced OpenImageIO memory-safety bugs. The 'Information Disclosure' tag CONFLICTS with the vendor vector (C:N) and overstates impact - this is a denial-of-service only. Realistic priority: patch during normal maintenance; it matters most for automated batch/render pipelines that ingest untrusted images, where a crash disrupts a job but does not compromise data.

An attacker submits a crafted, truncated TGA file to an automated pipeline (e.g., a render farm, asset-ingest service, or thumbnailer) that uses OpenImageIO to transcode it to GIF. The truncation leaves a pending GIF frame that is flushed at output-close, where a large image size overflows the signed 32-bit numPixels × partition-width product in GifSplitPalette(), corrupting subPixelsA and forcing an out-of-bounds read that crashes the process. No public exploit code was identified at time of analysis; exploitation is local and requires the victim to process the file.