CVE-2025-12840 – This is a heap-based buffer overflow vulnerabil... (How to Fix)

Q: What is the severity of CVE-2025-12840?

CVE-2025-12840 has a CVSS score of 7.8 (HIGH). This is a heap-based buffer overflow vulnerability in Academy Software Foundation OpenEXR's EXR file parsing. Attackers can execute arbitrary code by tricking users into opening malicious EXR files or visiting malicious web pages. Any system using vulnerable OpenEXR versions is affected.

📋 TL;DR

This is a heap-based buffer overflow vulnerability in Academy Software Foundation OpenEXR's EXR file parsing. Attackers can execute arbitrary code by tricking users into opening malicious EXR files or visiting malicious web pages. Any system using vulnerable OpenEXR versions is affected.

💻 Affected Systems

Products:

Academy Software Foundation OpenEXR

Versions: Specific vulnerable versions not specified in advisory, but likely multiple recent versions prior to patch.

Operating Systems: All platforms running OpenEXR (Windows, Linux, macOS)

Default Config Vulnerable: ⚠️ Yes

Notes: Any application that uses OpenEXR library to parse EXR files is vulnerable.

📦 What is this software?

Openexr by Openexr

View all CVEs affecting Openexr →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full remote code execution with current process privileges, potentially leading to complete system compromise.

🟠

Likely Case

Application crash or limited code execution depending on exploit sophistication and system protections.

🟢

If Mitigated

Application crash with no code execution if ASLR/DEP are properly implemented.

🌐 Internet-Facing: MEDIUM

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Requires user interaction (opening malicious file), but no authentication needed. Heap exploitation requires some sophistication.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check latest OpenEXR release after advisory date

Vendor Advisory: https://github.com/AcademySoftwareFoundation/openexr/security/advisories

Restart Required: Yes

Instructions:

1. Check current OpenEXR version
2. Update to latest patched version from official repository
3. Rebuild applications using OpenEXR
4. Restart affected services

🔧 Temporary Workarounds

File Type Restriction

all

Block or restrict EXR file processing in vulnerable applications

Application Sandboxing

all

Run OpenEXR applications in restricted environments

🧯 If You Can't Patch

Implement strict file upload validation for EXR files
Use application allowlisting to prevent unauthorized OpenEXR usage

🔍 How to Verify

Check if Vulnerable:

Check OpenEXR version against patched releases in vendor advisory

Check Version:

openexr_version or check library version in application

Verify Fix Applied:

Verify OpenEXR version is updated to patched release and test with known safe EXR files

📡 Detection & Monitoring

Log Indicators:

Application crashes when processing EXR files
Memory access violation errors in OpenEXR processes

Network Indicators:

Unexpected EXR file downloads to vulnerable systems

SIEM Query:

Process:openexr AND (EventID:1000 OR ExceptionCode:c0000005)

📊 Metadata

CVE ID: CVE-2025-12840

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-122

EPSS Score: 0.05% exploit probability (15.4th percentile)

Published: December 23, 2025

Last Updated: January 15, 2026

🔗 References

https://www.zerodayinitiative.com/advisories/ZDI-25-991/ Third Party Advisory

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