Medium · published July 28, 2026
Lookyloo did not enforce limits on the decompressed size of uploaded capture archives and compressed HAR files.
An attacker could submit a specially crafted ZIP, gzip, or zlib-compressed capture containing data that expands to a very large size during processing. Because the application decompressed this content directly in memory without first limiting the output size, processing the malicious capture could exhaust available memory, terminate a web or worker process, or make the Lookyloo instance unavailable.
The vulnerability affects both full Lookyloo capture archive imports and API submissions containing gzip-compressed HAR data. Repeated exploitation could cause a persistent denial-of-service condition until the affected processes or instance are restarted.
The patch introduces:
* A 1 GB cumulative uncompressed-size limit for imported capture archives.
* Size-limited gzip and zlib decompression for compressed HAR files.
* Explicit detection and handling of suspected zip bombs.
* An HTTP 400 response when an oversized compressed HAR file is submitted through the API.