ticofookfook/cve-2025-43300Detailed technical analysis of CVE-2025-43300, a buffer overflow vulnerability in DNG file processing enabling remote code execution. Explains the TIFF/JPEG metadata inconsistency, memory corruption mechanics, and exploit flow.
CVE-2025-43300 is a buffer overflow vulnerability in DNG (Digital Negative) file processing caused by an inconsistency between TIFF metadata and JPEG data, allowing remote code execution (RCE).
DNG File
├── TIFF Container (metadata)
│ ├── Header
│ ├── IFD (Image File Directory)
│ │ ├── Tag 277: SamplesPerPixel (declares how many components)
│ │ ├── Tag 513: JpegOffset (where JPEG starts)
│ │ └── Tag 514: JpegLength (JPEG size)
│ └── Other metadata
└── JPEG Data (actual image data)
├── SOI (Start of Image)
├── SOF0 (Frame Header)
│ └── Components: actual number of components
└── Compressed Data
// FUNDAMENTAL PROBLEM:
TIFF declares: "This image has 2 components" (SamplesPerPixel = 2)
JPEG contains: "Actually I have 3 components" (SOF0 Components = 3)
// Vulnerable code (simplified)
int samples = read_tiff_tag(277); // Reads 2
buffer = malloc(samples * sizeof(component)); // Allocates for 2
// But processes based on JPEG
int components = read_jpeg_sof0(); // Reads 3
for (int i = 0; i < components; i++) { // Loop 3 times!
buffer[i] = process_component(i); // OVERFLOW at i=2!
}
[1] FILE OPENING
↓
[2] TIFF PARSER
├─→ Reads TIFF Header
├─→ Locates IFD
├─→ Reads Tag 277 (SamplesPerPixel = 2)
└─→ Allocates buffer for 2 components
[3] JPEG LOCATION
├─→ Reads Tag 513 (JPEG offset)
└─→ Navigates to file position
[4] JPEG PARSER
├─→ Reads SOF0 marker (0xFFC0)
├─→ Extracts number of components (3)
└─→ DOES NOT VALIDATE against TIFF!
[5] PROCESSING
├─→ Loop to process 3 components
├─→ Buffer only has space for 2
└─→ 3rd component writes OUTSIDE the buffer
[6] BUFFER OVERFLOW
├─→ Overwrites adjacent data
├─→ Can overwrite return address
└─→ Enables execution control
[7] CODE EXECUTION
└─→ Attacker controls program flow
Stack Layout:
+----------------+ ← Top
| Buffer (2 comp)| [Component 0]
| | [Component 1]
+----------------+
| Local data |
+----------------+
| Frame Pointer |
+----------------+
| Return Address | ← Address to return to
+----------------+
Stack Layout:
+----------------+
| Buffer (2 comp)| [Component 0]
| | [Component 1]
+----------------+
| Local data | [Component 2] ← OVERFLOW!
+----------------+
| Frame Pointer | [Overwritten]
+----------------+
| Return Address | [Controlled by attacker]
+----------------+