Summary
The Docker API server's SSRF protection (validate_webhook_url / validate_url_destination in deploy/docker/utils.py) used an explicit IPv4/IPv6 CIDR blocklist that missed several address families. An attacker could reach internal services and cloud metadata endpoints (e.g. 169.254.169.254) despite the filter by encoding an internal IPv4 address inside an IPv6 transition form, or by using the IPv6 unspecified address.
Because the Docker API is unauthenticated by default (jwt_enabled: false), no credentials are required.
Affected paths
The blocklist was applied to crawl URLs (POST /crawl, /md, /html, /screenshot, /pdf, /execute_js) and webhook URLs (/crawl/job, /llm/job). All shared the same incomplete check.
Bypasses
The following all resolve to (or route to) blocked internal addresses but were NOT caught:
- IPv6 unspecified
:: - NAT64
64:ff9b::a9fe:a9fe(embeds169.254.169.254) - 6to4
2002:a9fe:a9fe::(embeds169.254.169.254) - IPv4-mapped
::ffff:169.254.169.254 - IPv4-compatible
::a9fe:a9fe
The error message also echoed the resolved internal IP, acting as a minor DNS/oracle leak.
Workarounds
- Upgrade to the patched version.
- Enable authentication (
CRAWL4AI_API_TOKEN). - Restrict the container's outbound network access (egress firewall / no metadata route).
Credits
Internal security audit (Crawl4AI maintainers).
Impact
Server-Side Request Forgery: an unauthenticated attacker can make the server fetch internal-network URLs and cloud instance-metadata endpoints, potentially exposing internal services and cloud credentials.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-53754 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.8.8); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
The blocklist is replaced by a single rule: reject any resolved IP where not ip.is_global, evaluated on the address AND every embedded IPv4 transition form (v4-mapped, NAT64 64:ff9b::/96, 6to4 2002::/16, v4-compat ::/96). Error messages are now opaque and no longer echo the resolved IP.
Frequently Asked Questions
- What is CVE-2026-53754? CVE-2026-53754 is a high-severity server-side request forgery (SSRF) vulnerability in crawl4ai (pip), affecting versions <= 0.8.7. It is fixed in 0.8.8. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-53754? CVE-2026-53754 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of crawl4ai are affected by CVE-2026-53754? crawl4ai (pip) versions <= 0.8.7 is affected.
- Is there a fix for CVE-2026-53754? Yes. CVE-2026-53754 is fixed in 0.8.8. Upgrade to this version or later.
- Is CVE-2026-53754 exploitable, and should I be worried? Whether CVE-2026-53754 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53754 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53754? Upgrade
crawl4aito 0.8.8 or later.