CVE-2026-47714 Overview
CVE-2026-47714 is an integer overflow vulnerability [CWE-190] in libheif, an open-source HEIF and AVIF file format decoder and encoder. The flaw resides in the inline mask parsing code within libheif/region.cc. Attackers can craft a malicious HEIF file that triggers an undersized buffer allocation, resulting in out-of-bounds memory access during mask processing. The vulnerability affects libheif versions 1.21.2 and prior. Version 1.22.0 contains the fix. Exploitation requires user interaction to open a crafted file locally.
Critical Impact
A malicious HEIF file can trigger an integer overflow leading to out-of-bounds memory access, causing application crashes or potential memory disclosure in any application linking libheif.
Affected Products
- libheif versions 1.21.2 and prior
- Applications and libraries embedding vulnerable libheif builds
- HEIF/AVIF processing pipelines using libheif/region.cc
Discovery Timeline
- 2026-07-21 - CVE-2026-47714 published to NVD
- 2026-07-22 - Last updated in NVD database
Technical Details for CVE-2026-47714
Vulnerability Analysis
The vulnerability exists in the inline mask parsing logic of libheif/region.cc. The parser reads two 32-bit unsigned integer fields, width and height, directly from the HEIF file. The code multiplies these values to compute the size of a bitmap buffer, then divides the product by 8 to derive the byte count for a packed 1-bit-per-pixel mask.
Both operands are attacker-controlled. Their product can exceed UINT32_MAX, causing the arithmetic to wrap around to a small value before the division by 8. The resulting allocation is far smaller than the logical mask size the code later assumes. When the parser reads or writes the mask data as a width x height bitmap, it steps outside the allocated buffer.
The issue is classified as an integer overflow [CWE-190] leading to a heap buffer under-allocation and subsequent out-of-bounds access. Exploitation requires a local file open and user interaction, per the CVSS vector.
Root Cause
The root cause is missing overflow checks on the width * height multiplication before allocation. The code trusts values parsed from an untrusted container without validating that the arithmetic result fits within a 32-bit unsigned integer or that the resulting size matches the buffer capacity.
Attack Vector
An attacker distributes a crafted HEIF or AVIF file containing an inline region mask with oversized width and height fields whose product wraps UINT32_MAX. When a user opens the file with an application built on vulnerable libheif, the parser allocates a small buffer and reads or writes mask data beyond its bounds. This can cause process crashes, memory corruption, or disclosure of adjacent heap memory.
See the GitHub Security Advisory GHSA-h4wm-6wwf-qvhx for the upstream technical description.
Detection Methods for CVE-2026-47714
Indicators of Compromise
- Unexpected crashes or heap corruption in processes linking libheif when opening HEIF or AVIF content
- HEIF files containing region items with implausibly large width or height values in inline mask records
- ASAN or sanitizer reports pointing to libheif/region.cc during file parsing
Detection Strategies
- Inventory installed libheif versions across build systems and container images, flagging any version at or below 1.21.2
- Scan image processing pipelines and third-party applications for bundled libheif shared libraries
- Enable AddressSanitizer or heap protection in test environments to surface out-of-bounds access when processing untrusted HEIF samples
Monitoring Recommendations
- Monitor endpoint telemetry for abnormal termination of image viewers, thumbnailers, and file indexers processing HEIF or AVIF files
- Alert on repeated crashes of the same process consuming user-supplied media, which often indicates fuzzing or exploitation attempts
- Log HEIF and AVIF file downloads originating from untrusted sources for retrospective analysis
How to Mitigate CVE-2026-47714
Immediate Actions Required
- Upgrade libheif to version 1.22.0 or later on all systems and container images
- Rebuild and redistribute downstream applications and packages that statically link libheif
- Identify user-facing consumers of HEIF and AVIF such as image viewers, previewers, and web upload pipelines, and prioritize their updates
Patch Information
The libheif maintainers fixed CVE-2026-47714 in version 1.22.0. The fix adds overflow-safe size computation in the inline mask parser in libheif/region.cc. Refer to the GitHub Security Advisory GHSA-h4wm-6wwf-qvhx for release notes and commit references.
Workarounds
- Restrict processing of HEIF and AVIF files from untrusted sources until libheif is upgraded
- Sandbox image parsing components using seccomp, AppArmor, or containerization to limit blast radius from memory corruption
- Disable HEIF and AVIF handlers in file managers and thumbnail services where the formats are not required
# Verify installed libheif version
heif-info --version
# Example: upgrade on Debian-based systems once the fixed package is available
sudo apt update && sudo apt install --only-upgrade libheif1
# Confirm remediation
dpkg -l | grep libheif
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
