# CVE-2026-66913: Zip Bomb in Lookyloo Capture Upload Allows Denial of Service

> Attackers can cause denial of service in Lookyloo by uploading zip bombs that exhaust memory during decompression.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026

## What is CVE-2026-66913?

CVE-2026-66913 is a medium-severity denial of service vulnerability in lookyloo, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-66913?


## How do I fix CVE-2026-66913?

No fix has been published for CVE-2026-66913 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66913 being exploited?

There is no known exploitation of CVE-2026-66913 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66913 and fix it if it is affected.

What it is: CVE-2026-66913 is a medium-severity denial of service vulnerability in lookyloo, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-66913 in the wild and no public exploit code.

Affected product: lookyloo. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66913/ (Markdown: https://insights.sbomify.com/CVE-2026-66913/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66913
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66913
- OSV: https://osv.dev/vulnerability/CVE-2026-66913

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66913/
Summaries are generated and may contain mistakes; the official description above is the record.