Listen to this Post
This vulnerability exists in the model loading functionality of SentencePiece, a text tokenization library. The heap overflow occurs when the library processes a maliciously crafted model file. During the deserialization process, the code reads a 32-bit integer from the file header specifying the size of a future data chunk. This value is not properly validated. When the library later reads the actual chunk data using this unchecked size, it allocates a heap buffer based on the expected size but copies an amount of data controlled by the attacker-defined size value. This mismatch between the allocated buffer size and the copied data length results in a heap-based buffer overflow. An attacker can exploit this by providing a model file with a manipulated size field, causing the memory copy operation to write beyond the allocated buffer’s boundary, corrupting adjacent heap metadata and data structures, which can lead to arbitrary code execution or a denial-of-service crash.
Platform: SentencePiece library
Version: < 0.2.1
Vulnerability: Heap Overflow
Severity: High
Date: 2026-01-22
Prediction: 2026-02-12
What Undercode Say:
`strings malicious.model | grep -a “sentencepiece”`
`valgrind –tool=memcheck spm_encode –model=malicious.model`
`python3 -c “import sentencepiece; sp = sentencepiece.SentencePieceProcessor(); sp.Load(‘malicious.model’)”`
How Exploit:
Craft model header.
Set oversized length field.
Trigger deserialization path.
Overflow heap buffer.
Control program execution.
Protection from this CVE
Update to 0.2.1.
Validate model files.
Use trusted sources.
Apply input sanitization.
Impact:
Arbitrary Code Execution.
Denial of Service.
System Compromise.
Memory Corruption.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
