CVE-2025-48379

What it actually does

Heap buffer overflow when writing a sufficiently large compressed DDS image due to lack of bounds checking before writing into the output buffer.

Why it matters to the business

Applications that save untrusted image data as compressed DDS files may crash or allow arbitrary code execution, disrupting image-processing workflows and exposing systems that handle user-supplied graphics.

How an attack unfolds

An attacker supplies a large DDS image file; when the vulnerable Pillow library writes it in compressed DDS format, the missing size check causes a write past the allocated buffer, potentially corrupting heap memory for code execution.

How to fix it

Upgrade python-pillow/pillow to version 11.3.0 or apply commit 89f1f4626a2aaf5f3d5ca6437f41def2998fbe09. Avoid saving untrusted data as compressed DDS until patched.

How to confirm the fix worked

Confirm Pillow version is 11.3.0 or newer; attempt to save a >64 kB compressed DDS image and verify no crash or overflow occurs.

Typical attack path

1. Craft or obtain a DDS image exceeding 64 kB when compressed with default settings
2. Cause the target application to call Pillow's DDS save routine on the untrusted image
3. Trigger the unchecked buffer write that overflows the heap allocation
4. Leverage the resulting memory corruption to execute arbitrary code or crash the process

How to detect it

Review application logs for unexpected crashes or segmentation faults during DDS save operations; inspect heap-related error messages or memory corruption indicators in crash dumps from processes using Pillow.

What your security team should do

• Immediately upgrade all Pillow installations to 11.3.0
• Restrict or sanitize untrusted image inputs before DDS compression
• Monitor for crashes in image-processing services that accept DDS files
• Review downstream dependencies that rely on Pillow for DDS handling