CVE-2025-43962: LibRaw Buffer Overflow Vulnerability

CVE-2025-43962 Overview

CVE-2025-43962 is an out-of-bounds read vulnerability discovered in LibRaw, a widely-used library for reading RAW image files from digital cameras. The vulnerability exists in the phase_one_correct function within decoders/load_mfbacks.cpp and affects versions prior to 0.21.4. When processing tag 0x412, the function fails to properly validate w0 and w1 values derived from header calculations, as well as related frac and mult calculations. This can lead to out-of-bounds memory reads when processing maliciously crafted RAW image files.

Critical Impact

Attackers can exploit this vulnerability to read sensitive information from memory or cause application crashes through malicious RAW image files, potentially leading to information disclosure or denial of service conditions.

Affected Products

• LibRaw versions prior to 0.21.4
• Applications and software that depend on LibRaw for RAW image processing
• Linux distributions using vulnerable LibRaw packages (including Debian LTS)

Discovery Timeline

• 2025-02-05 - Security fix committed by Alex Tutubalin
• 2025-04-21 - CVE CVE-2025-43962 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-43962

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-bounds Read), affecting the phase_one_correct function responsible for processing Phase One camera corrections in RAW image files. The function reads header values from image data and uses them to calculate buffer sizes without adequate validation. Specifically, when processing tag 0x412, the function computes two values: w0 (from head[1] * head[3]) and w1 (from head[2] * head[4]). These computed values directly influence memory allocation and subsequent read operations.

The vulnerability can be exploited remotely without authentication by crafting a malicious RAW image file containing manipulated header values. When a vulnerable application parses such a file using LibRaw, the excessively large w0 or w1 values can trigger out-of-bounds read operations, potentially exposing sensitive memory contents or causing application crashes.

Root Cause

The root cause is insufficient input validation for header values read from RAW image files. The original code trusted that header values would produce reasonable buffer size calculations. By providing artificially large values in the RAW file headers, an attacker could force the library to calculate excessively large w0 and w1 values, leading to out-of-bounds memory access during subsequent processing operations.

Attack Vector

The attack can be executed remotely over a network by delivering a malicious RAW image file to a target system. No authentication or user interaction beyond opening the file is required. Attack scenarios include:

1. Embedding malicious RAW files in email attachments
2. Hosting malicious images on websites for download
3. Including malicious files in image galleries or content management systems
4. Exploiting applications that automatically process uploaded images

The vulnerability allows attackers to read memory beyond allocated buffer boundaries, which could expose sensitive information or cause denial of service through application crashes.

// Security patch in src/decoders/load_mfbacks.cpp - Prevent out-of-bounds read in fuji 0xf00c tag parser
       fseek(ifp, off_412, SEEK_SET);
       for (i = 0; i < 9; i++)
         head[i] = get4() & 0x7fff;
+	  unsigned w0 = head[1] * head[3], w1 = head[2] * head[4];
+	  if (w0 > 10240000 || w1 > 10240000)
+		  throw LIBRAW_EXCEPTION_ALLOC;
       yval[0] = (float *)calloc(head[1] * head[3] + head[2] * head[4], 6);
       yval[1] = (float *)(yval[0] + head[1] * head[3]);
       xval[0] = (ushort *)(yval[1] + head[2] * head[4]);

Source: GitHub Commit Reference

Detection Methods for CVE-2025-43962

Indicators of Compromise

• Unexpected application crashes when processing RAW image files, particularly Phase One format files
• Memory access violation errors in applications using LibRaw
• Abnormal memory consumption patterns when handling image files
• Application logs showing exceptions related to allocation errors in LibRaw

Detection Strategies

• Monitor for crashes or exceptions in applications utilizing LibRaw for RAW image processing
• Implement file integrity monitoring on systems that process untrusted RAW image uploads
• Deploy application-level monitoring to detect unusual memory access patterns
• Use memory sanitizers (AddressSanitizer) in development/testing environments to identify out-of-bounds reads

Monitoring Recommendations

• Enable detailed logging for image processing workflows to capture error conditions
• Implement input validation and file type verification before processing RAW images
• Monitor system resources for abnormal memory consumption during image processing operations
• Set up alerts for application crashes related to image processing libraries

How to Mitigate CVE-2025-43962

Immediate Actions Required

• Upgrade LibRaw to version 0.21.4 or later immediately
• Audit all applications and dependencies that use LibRaw for RAW image processing
• Restrict untrusted RAW file uploads until systems are patched
• Implement input validation for image files before processing

Patch Information

The vulnerability has been fixed in LibRaw version 0.21.4. The patch adds bounds checking for the computed w0 and w1 values, rejecting any values exceeding 10,240,000 by throwing a LIBRAW_EXCEPTION_ALLOC exception. This prevents malicious files from triggering out-of-bounds read operations.

The security fix is available through:

• GitHub Commit 66fe663
• LibRaw 0.21.4 Release
• Debian LTS Security Update

Workarounds

• Disable processing of untrusted RAW image files until patches can be applied
• Implement file validation to reject RAW files from untrusted sources
• Use sandboxed environments for processing potentially malicious image files
• Consider application-level filtering to limit accepted image formats

# Configuration example
# Check current LibRaw version
pkg-config --modversion libraw

# Update LibRaw on Debian-based systems
sudo apt update && sudo apt upgrade libraw-dev

# Verify the patched version (0.21.4 or higher)
pkg-config --modversion libraw | awk -F. '{if ($1 >= 0 && $2 >= 21 && $3 >= 4) print "Patched"; else print "Vulnerable"}'