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The vulnerability in Seroval, a serialization library, arises from how array lengths are handled during the serialization and deserialization process. In the affected versions, Seroval encoded array lengths directly into the serialized data stream. During deserialization, the library reads this encoded length value to determine how many array elements to process. An attacker can exploit this by crafting malicious serialized data where the encoded array length is replaced with an excessively large integer, such as a number significantly beyond practical array sizes. When the deserialization function processes this manipulated data, it attempts to iterate or allocate resources based on the fake large length. Since the actual array elements in the data stream are fewer or absent, the deserialization process enters a state where it spends disproportionate time and computational resources trying to handle the non-existent elements. This can lead to a severe denial of service (DoS) condition, as the process may hang, consume high CPU, or cause memory exhaustion, rendering the application unresponsive. The root cause is the trust in unvalidated, user-supplied length values during deserialization, without bounds checking or fallback mechanisms. The mitigation involves removing the encoding of array lengths altogether and instead computing the length dynamically during deserialization using Array.prototype.length, which relies on the actual data structure rather than a transmitted value, thus preventing manipulation.
Platform: Seroval
Version: Not specified
Vulnerability: Denial of Service
Severity: High
Date: Jan 21, 2026
Prediction: Patched Jan 21, 2026
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bash
git clone https://github.com/lxsmnsyc/seroval
cd seroval
npm test
javascript
// Example malicious payload
const maliciousData = serialize([1,2,3]);
maliciousData = overwriteLength(maliciousData, 1000000000);
deserialize(maliciousData); // Causes DoS
How Exploit
Craft serialized data with oversized length value.
Protection from this CVE
Use patched version without encoded lengths.
Impact:
Application denial of service.
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Sources:
Reported By: github.com
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