CVE-2026-53754 — crawl4ai
HIGHCVE-2026-53754 is a high-severity (CVSS 7.5) Server-Side Request Forgery (SSRF) vulnerability in crawl4ai. A fix is available for crawl4ai — see the affected versions and patch details below.
Crawl4AI: SSRF filter bypass in Docker server via IPv6 transition forms (NAT64 / 6to4 / unspecified / v4-mapped)
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53754.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-53754 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
crawl4aiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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.
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.
Fix
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.
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).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | crawl4ai | all versions | 0.8.8pip install --upgrade 'crawl4ai==0.8.8' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for crawl4ai, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update crawl4ai to 0.8.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53754 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-53754 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-53754. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-53754 in your dependencies?
O3 Security finds CVE-2026-53754 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.