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🛡️ CVE-2026-53755 — crawl4ai

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-918 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Crawl4AI: SSRF via proxy settings in the Docker server bypasses the crawl-URL SSRF check

Summary

The Docker API server applied its SSRF destination check to the crawl target URL only, not to the proxy address. An unauthenticated request could supply a proxy pointing at an internal IP and route the browser through it, reaching internal services and cloud-metadata endpoints, while using a perfectly valid crawl URL. The Docker API is unauthenticated by default.

Affected paths

/crawl, /crawl/stream, and /crawl/job accept a browser_config (and crawler_config). The following all feed Chromium's egress and were unchecked:

  • browser_config.proxy_config.server
  • browser_config.proxy (deprecated field)
  • crawler_config.proxy_config.server
  • --proxy-server / --proxy-pac-url / --proxy-bypass-list / --host-resolver-rules flags in browser_config.extra_args

Attack

An attacker sends /crawl with a benign, validation-passing URL but a proxy_config.server pointing at an internal IP. Chromium routes all requests through that proxy. For plain-HTTP targets the proxy receives the full request and can return any content, which is then returned verbatim in the crawl result (results[0].html / cleaned_html / markdown). In a real deployment the proxy would be an attacker-controlled server pointing at cloud metadata (e.g. AWS IMDSv1 at 169.254.169.254) to retrieve IAM credential tokens.

Impact

Unauthenticated server-side request forgery to internal services and cloud-metadata endpoints, with the response returned to the attacker.

Fix

Every proxy destination is validated with the same global-routability check used for crawl URLs (reject any resolved address that is not is_global, including IPv6 transition forms) before the browser is constructed; proxy/DNS-redirecting flags are stripped from extra_args. A legitimate public proxy still works. Honors CRAWL4AI_ALLOW_INTERNAL_URLS.

Workarounds

  • Upgrade to the patched version (0.8.9).
  • Enable authentication (CRAWL4AI_API_TOKEN).
  • Restrict the container's outbound network access (egress firewall / no metadata route).

Credits

Geo ([geo-chen](https://github.com/geo-chen)) - reported the proxy_config.server SSRF with a clear PoC.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-53755 is classified as CWE-918: Server-Side Request Forgery (SSRF). The server fetches a URL supplied by the caller, which can be pointed at internal systems it alone can reach.

Affected software

CVE-2026-53755 is recorded against 1 package.

  • crawl4ai (fixed in 0.8.9)

Timeline and source

Published on 23 June 2026 and last revised on 20 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Advisory)

Other advisories for this package

crawl4ai has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-918: Server-Side Request Forgery (SSRF)) in other software:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE CWE-918
Public Exploit ✅ No
Source OSV
Published 2026-06-23
Updated 2026-08-20
Modified 2026-07-20
Fix URL N/A

Affected Packages

Software From version Fixed in
crawl4ai — 0.8.9

Similar Threats

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