high CVSS 8.6

CVE-2026-53755·Docker vulnerability

Crawl4AI is an open-source LLM friendly web crawler & scraper. Prior to 0.8.9, 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. /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, and --proxy-server / --proxy-pac-url / --proxy-bypass-list / --host-resolver-rules flags in browser_config.extra_args. This vulnerability is fixed in 0.8.9.

Severity
high
Software
Docker
Fixed in
0.8.9
Published
2026-06-23

Affected versions

Until: 0.8.9

Fixed in: 0.8.9

How to fix this CVE

Update Docker to the latest version to patch the SSRF vulnerability in Crawl4AI's API server. The vulnerability allows unauthenticated attackers to bypass destination validation by routing requests through proxy configurations, potentially exposing internal services and cloud metadata endpoints. Upgrade to version 0.8.9 or later immediately, and review any Docker deployments exposing the /crawl, /crawl/stream, or /crawl/job endpoints without authentication controls.

sudo dnf update docker-ce

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST /crawl HTTP/1.1 with JSON payload containing proxy_config.server, proxy, or extra_args fields pointing to non-routable IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or cloud metadata endpoints (169.254.169.254); also monitor for proxy_pac_url, proxy_bypass_list, or host_resolver_rules parameters with suspicious values.

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement authentication on all Crawl4AI API endpoints (/crawl, /crawl/stream, /crawl/job) using API keys or OAuth; validate and whitelist proxy addresses against an internal registry before accepting requests; block requests containing proxy_config, proxy, extra_args, proxy_pac_url, or host_resolver_rules parameters unless from trusted sources; log all requests with proxy parameters for anomaly detection.

How to check if you are affected

  1. Run `docker --version` to check your installed Docker version; versions prior to 0.8.9 are vulnerable if Crawl4AI is deployed.
  2. Check if Crawl4AI is running by executing `docker ps | grep crawl4ai` and inspect container logs with `docker logs <container_id> | grep -i proxy`.
  3. Review Docker daemon configuration and environment variables for proxy_config, proxy_server, or proxy settings: `env | grep -i proxy` and inspect mounted volumes for crawler configuration files.
  4. After patching, verify the update with `docker --version` and confirm Crawl4AI version is 0.8.9+ by checking the container image tag or running `curl http://localhost:8000/health` if the API is accessible.

FAQ

What is CVE-2026-53755?

CVE-2026-53755 is a Server-Side Request Forgery (SSRF) vulnerability in Crawl4AI's Docker API server that fails to validate proxy addresses supplied in browser and crawler configurations, allowing unauthenticated attackers to route requests through internal proxies to reach restricted services and cloud metadata endpoints.

Is CVE-2026-53755 being actively exploited?

No, this vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities catalog and no public exploits are available, but the unauthenticated nature of the vulnerable endpoints makes it a high-risk exposure if the API is internet-facing.

What versions of Docker are affected by CVE-2026-53755?

All versions of Crawl4AI prior to 0.8.9 are affected when deployed in Docker; update to 0.8.9 or later to remediate the proxy validation bypass.

How do I check if my server is vulnerable to CVE-2026-53755?

Run `docker images | grep crawl4ai` to list deployed images and check their tags; if any version is below 0.8.9, the deployment is vulnerable. Additionally, test accessibility of the API endpoints: `curl -X POST http://localhost:8000/crawl -H 'Content-Type: application/json' -d '{"url": "http://example.com"}' | grep -i error` to confirm if the API is exposed.

Does Defensia detect CVE-2026-53755?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker or Crawl4AI containers are running on a monitored server, CVE-2026-53755 will appear in your dashboard with remediation steps and version comparison details.

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CVE-2026-57572CVSS 10Crawl4AI is an open-source LLM-friendly web crawler and scraper. Prior to 0.9.0, the Docker API server accepted request-supplied browser_config.extra_args, which flowed into Chromium's launch arguments. An attacker could inject Chromium switches that replace a child-process launch command together with --no-zygote, causing Chromium to fork or exec an attacker-controlled command as the container's runtime user. The Docker API is unauthenticated by default, so a single request yields arbitrary command execution. This issue is fixed in version 0.9.0.
CVE-2026-53576CVSS 10Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter for the REST API (@Filter("/api/v1/**")) treats any request whose path ends in /configs as the public instance-config endpoint and forwards it without a credential check. kestra addresses its resources by URL path segments that the caller chooses (/api/v1/{tenant}/flows/{namespace}, /api/v1/{tenant}/executions/{namespace}/{id}, /api/v1/{tenant}/namespaces/{namespace}/kv/{key}). An anonymous caller picks the literal configs as the final segment, and the request bypasses Basic-Auth entirely. Because the bypass reaches the flow-create and execution-trigger routes, an unauthenticated caller creates a flow containing a Shell or Process task and runs it. The task executes as root inside the kestra container. The official docker-compose.yml mounts /var/run/docker.sock, so root in the container reaches the host Docker daemon. This vulnerability is fixed in 1.0.45 and 1.3.21.
CVE-2026-33587CVSS 10Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and subsequently OS commands) on the docker container via Server-Side Template Injection (SSTI) for user-created transformations.
CVE-2026-26216CVSS 10Crawl4AI versions prior to 0.8.0 contain a remote code execution vulnerability in the Docker API deployment. The /crawl endpoint accepts a hooks parameter containing Python code that is executed using exec(). The __import__ builtin was included in the allowed builtins, allowing unauthenticated remote attackers to import arbitrary modules and execute system commands. Successful exploitation allows full server compromise, including arbitrary command execution, file read and write access, sensitive data exfiltration, and lateral movement within internal networks.

References

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