Heap-Based Buffer Overflow in LibRaw x3f_load_huffman Function

Executive Summary

CVE-2026-24660 is a heap-based buffer overflow vulnerability in the x3f_load_huffman() function of the LibRaw library, which processes RAW image files, specifically Sigma/Foveon X3F files using Huffman compression.

The vulnerability occurs due to an integer overflow when calculating the buffer size for decompressed RAW data. The function multiplies image dimensions (columns and rows) by 3 using 32-bit arithmetic, which can overflow if the product exceeds the maximum 32-bit unsigned integer value.

This overflow causes the allocated buffer to be smaller than needed, but the Huffman decoder writes data based on the original dimensions, leading to out-of-bounds writes and heap buffer overflow.

Exploitation requires large image dimensions and specific configuration settings (e.g., max_raw_memory_mb above ~11 GB) and only occurs if LibRaw is compiled with X3F support enabled.

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Impact Analysis

This vulnerability can lead to heap corruption and potentially allow an attacker to execute arbitrary code when processing specially crafted malicious X3F image files.

Because the vulnerability involves out-of-bounds writes on the heap, it can compromise the stability and security of applications using the vulnerable LibRaw version, potentially leading to crashes or full system compromise.

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Detection Guidance

This vulnerability occurs when processing specially crafted X3F RAW image files with large dimension values using the LibRaw library compiled with X3F support enabled. Detection involves identifying if your system uses a vulnerable version of LibRaw with X3F support and if it processes untrusted X3F files.

To detect attempts to exploit this vulnerability, monitor for crashes or heap-buffer-overflow errors related to the x3f_load_huffman() function, especially when handling large X3F files.

Suggested commands include running AddressSanitizer or similar memory error detection tools on applications using LibRaw to process X3F files, which can reveal heap buffer overflows.

Additionally, you can check the version and build options of LibRaw on your system to confirm if X3F support is enabled (look for the -DUSE_X3FTOOLS compile flag). For example, use commands like:

• ldd $(which your_application) | grep libraw # To check if libraw is linked
• strings /path/to/libraw.so | grep X3F # To check for X3F support indications
• Run your application with AddressSanitizer enabled or use tools like Valgrind to detect heap buffer overflows when processing suspicious X3F files.

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Mitigation Strategies

The immediate mitigation step is to update LibRaw to the patched version released on 2026-04-06 that fixes this heap-based buffer overflow vulnerability.

If updating is not immediately possible, consider disabling or avoiding processing of X3F RAW image files, especially those with very large dimensions, as exploitation requires large image sizes.

Also, ensure that the max_raw_memory_mb parameter is set to a safe limit (below approximately 11 GB) to prevent processing of excessively large images that could trigger the vulnerability.

Finally, if you compile LibRaw yourself, disable X3F support by not using the -DUSE_X3FTOOLS flag until a patched version is available.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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