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CVE-2026-66913

Zip Bomb in Lookyloo Capture Upload Allows Denial of Service

6.9 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.43%Up 0.2 points since Jul 29, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.9

Zip Bomb in Lookyloo Capture Upload Allows Denial of Service

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.
Record
CVE-2026-66913
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-400
Updated
2026-11-02
EUVDEUVD-2026-49768 6.9

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.
Record
EUVD-2026-49768
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 6.9

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.
Record
CVE-2026-66913
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-400
Updated
2026-11-02
OSV 6.9

Zip Bomb in Lookyloo Capture Upload Allows Denial of Service

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.
Record
CVE-2026-66913
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-400
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-66913 is a medium vulnerability (CVSS 6.9) in Lookyloo, published July 28, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.43%, the 37th percentile. No source names a fixed version.

References

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