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.
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-66913",
"assignerOrgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
"assignerShortName": "CIRCL",
"dateUpdated": "2026-07-28T12:19:20.977Z",
"dateReserved": "2026-07-28T12:19:10.431Z",
"datePublished": "2026-07-28T12:19:20.977Z",
"state": "PUBLISHED"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
"shortName": "CIRCL",
"dateUpdated": "2026-07-28T12:19:20.977Z"
},
"title": "Zip Bomb in Lookyloo Capture Upload Allows Denial of Service",
"descriptions": [
{
"lang": "en",
"value": "Lookyloo did not enforce limits on the decompressed size of uploaded capture archives and compressed HAR files.\n\nAn 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.\n\nThe 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.\n\nThe patch introduces:\n\n * A 1 GB cumulative uncompressed-size limit for imported capture archives.\n * Size-limited gzip and zlib decompression for compressed HAR files.\n * Explicit detection and handling of suspected zip bombs.\n * An HTTP 400 response when an oversized compressed HAR file is submitted through the API.",
"supportingMedia": [
{
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"value": "<p>Lookyloo did not enforce limits on the decompressed size of uploaded capture archives and compressed HAR files.</p><p>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.</p><p>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.</p><p>The patch introduces:</p><ul><li>A 1 GB cumulative uncompressed-size limit for imported capture archives.</li><li>Size-limited gzip and zlib decompression for compressed HAR files.</li><li>Explicit detection and handling of suspected zip bombs.</li><li>An HTTP 400 response when an oversized compressed HAR file is submitted through the API.</li></ul><br>"
}
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"affected": [
{
"vendor": "lookyloo",
"product": "lookyloo",
"repo": "https://github.com/Lookyloo/lookyloo",
"defaultStatus": "unaffected",
"versions": [
{
"version": "0",
"status": "affected",
"versionType": "semver",
"lessThanOrEqual": "1.40.0"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"description": "CWE-400 Uncontrolled Resource Consumption",
"cweId": "CWE-400",
"type": "CWE"
}
]
}
],
"references": [
{
"url": "https://github.com/Lookyloo/lookyloo/commit/96589da290f018e356db7c0eaddf1aa501630ca7",
"tags": [
"patch"
]
}
],
"impacts": [
{
"capecId": "CAPEC-490",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-490 Amplification"
}
]
}
],
"metrics": [
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"format": "CVSS",
"scenarios": [
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"lang": "en",
"value": "GENERAL"
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}
],
"credits": [
{
"lang": "en",
"value": "Raphael Vinot",
"type": "remediation developer"
},
{
"lang": "en",
"value": "https://github.com/EQSTLab",
"type": "finder"
}
]
}
}
}