CVE-2026-57571
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCrawl4AI is an open-source LLM-friendly web crawler and scraper. Prior to 0.9.0, when the crawler saves a downloaded file, the destination filename was taken from attacker-influenced input and joined to the downloads directory with no confinement. A filename containing an absolute path or traversal escaped the downloads directory, giving an arbitrary file write with attacker-controlled contents; the HTTP crawler path uses the response Content-Disposition filename and the browser crawler path uses the download's suggested filename. Because the written bytes are attacker-controlled, this can escalate to remote code execution. This issue is fixed in version 0.9.0.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCrawl4AI versions prior to 0.9.0 contain a path traversal vulnerability in the file download functionality. When saving downloaded files, the application uses attacker-influenced filename input (Content-Disposition header for HTTP crawler, suggested filename for browser crawler) without sanitization, allowing attackers to specify absolute paths or traversal sequences to write files outside the intended downloads directory. This arbitrary file write can be chained to achieve remote code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 0.9.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check Crawl4AI versionRun 'pip show crawl4ai' or check your package manager to identify the installed version of Crawl4AIAffected if The installed version is below 0.9.0 (e.g., 0.8.x, 0.7.x, etc.)
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Identify if file download/save feature is usedReview your Crawl4AI configuration or code for usage of features that save downloaded files or media (e.g., save_as_html, save_media, save_screenshots, or similar options)Affected if The feature that saves downloaded content to disk is enabled in your crawler configuration or API calls
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Check downloads directory for unexpected filesInspect the configured downloads output directory for files with unusual names, especially those containing '../' patterns, absolute paths like '/tmp/', or unexpected extensions in locations outside the intended folderAffected if Files exist outside the designated downloads directory or have suspicious traversal patterns in their names
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Review access logs for traversal patternsExamine crawler logs or HTTP access logs for requests where Content-Disposition headers or filename parameters contain '../' sequences or absolute path patternsAffected if Logs show requests with path traversal sequences in filename parameters being processed by Crawl4AI
You are affected if you are running Crawl4AI version below 0.9.0 and actively using features that save downloaded files to disk, as the vulnerability allows escaping the downloads directory through unsanitized filenames.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.9.0
Upgrade to Crawl4AI version 0.9.0 or later. If upgrading is not immediately feasible, implement path validation to ensure filenames resolve within the intended downloads directory and reject absolute paths or traversal sequences (..).
0.9.0
- Upgrade Crawl4ai to version 0.9.0 or later using your package manager (e.g., pip install crawl4ai==0.9.0 or pip install crawl4ai>=0.9.0)
- After upgrading, verify that file downloads are now properly sanitized and path traversal is prevented
- Test the download functionality to confirm the fix works as expected
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-57571 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-57571 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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