---
id: CVE-2026-55373
title: >-
  OpenEXR is the reference implementation and specification for the EXR image
  format, widely used in the motion picture industry
summary: >-
  OpenEXR is the reference implementation and specification for the EXR image
  format, widely used in the motion picture industry. Versions prior to 3.2.10,
  3.3.12, and 3.4.13 contain an infinite-loop vulnerability in
  SampleCountChannel. Th…
severity: medium
cvss: 6.2
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-190
  - CWE-400
  - CWE-835
published: '2026-08-25'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:07:31.353'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55373'
references:
  - url: >-
      https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-mff9-68x3-h8rh
    label: security-advisories@github.com
  - url: >-
      https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-mff9-68x3-h8rh
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00157
epssPercentile: 0.04132
ingestedAt: '2026-09-09T21:22:45.550Z'
---

## Overview

OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. Versions prior to 3.2.10, 3.3.12, and 3.4.13 contain an infinite-loop vulnerability in SampleCountChannel. The helper roundListSizeUp() rounds a sample-list size up to the next power of two using repeated unsigned left shifts, which terminates for normal values but fails for UINT_MAX: the sequence reaches 0x80000000, and the next left shift wraps the 32-bit value to 0. Because 0 remains less than UINT_MAX, the loop never progresses and never exits. The bug is reachable through public OpenEXRUtil APIs, either by editing the sample-count buffer through SampleCountChannel::Edit (whose destructor calls endEdit()) or by calling SampleCountChannel::set(x, y, UINT_MAX) on a valid pixel. This issue has been fixed in versions 3.2.10, 3.3.12, and 3.4.13.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.