CVE-2026-53754: Crawl4AI SSRF Filter Bypass Vulnerability
HIGHCVE-2026-53754 is a HIGH (CVSS 7.5) ssrf filter bypass vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Crawl4AI libraries in the PyPI ecosystem. The issue involves ssrf filter bypass in docker server via ipv6 transition forms (nat64 / 6to4 / unspecified / v4-mapped). Remediation is available by upgrading affected packages to version 0.8.8.
CVE-2026-53754 at a Glance
Security Impact
CVSS: 7.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
How to Fix CVE-2026-53754
To remediate this vulnerability, upgrade all affected Crawl4AI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
pip install crawl4ai>=0.8.8Run the following command in your project directory to verify that all resolved dependencies use the patched release:
pip show crawl4aiHow to Check if You Are Affected
To determine whether your Python environment is affected by CVE-2026-53754, inspect your installed packages using pip:
pip show crawl4aiAnalyze the terminal output to locate any version of Crawl4AI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.8.8), your application is affected.
Note: The pip show crawl4ai command checks currently installed packages in your active Python environment.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In Crawl4AI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-53754 Affected Crawl4AI Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
crawl4ai
|
PyPI |
< 0.8.8
|
0.8.8
|
References
Frequently Asked Questions
What is CVE-2026-53754?
Which Crawl4AI versions are affected?
What version fixes CVE-2026-53754?
Is crawl4ai affected?
What is the CVSS score of CVE-2026-53754?
What CWE is associated with CVE-2026-53754?
How can I check PyPI dependencies for CVE-2026-53754?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-4qqr-vv2q-cmr5",
"modified" : "2026-07-20T21:12:00Z",
"published" : "2026-06-16T21:00:04Z",
"aliases" : [ "CVE-2026-53754" ],
"summary" : "Crawl4AI: SSRF filter bypass in Docker server via IPv6 transition forms (NAT64 / 6to4 / unspecified / v4-mapped)",
"details" : "### Summary\n\nThe 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.\n\nBecause the Docker API is unauthenticated by default (`jwt_enabled: false`), no credentials are required.\n\n### Affected paths\n\nThe 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.\n\n### Bypasses\n\nThe following all resolve to (or route to) blocked internal addresses but were NOT caught:\n- IPv6 unspecified `::`\n- NAT64 `64:ff9b::a9fe:a9fe` (embeds `169.254.169.254`)\n- 6to4 `2002:a9fe:a9fe::` (embeds `169.254.169.254`)\n- IPv4-mapped `::ffff:169.254.169.254`\n- IPv4-compatible `::a9fe:a9fe`\n\nThe error message also echoed the resolved internal IP, acting as a minor DNS/oracle leak.\n\n### Impact\n\nServer-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.\n\n### Fix\n\nThe 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.\n\n### Workarounds\n\n- Upgrade to the patched version.\n- Enable authentication (`CRAWL4AI_API_TOKEN`).\n- Restrict the container's outbound network access (egress firewall / no metadata route).\n\n### Credits\n\nInternal security audit (Crawl4AI maintainers).",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "PyPI",
"name" : "crawl4ai"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "0.8.8"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 0.8.7"
}
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/unclecode/crawl4ai/security/advisories/GHSA-4qqr-vv2q-cmr5"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-53754"
}, {
"type" : "WEB",
"url" : "https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-587.yaml"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/unclecode/crawl4ai"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-06-16T21:00:04Z",
"nvd_published_at" : "2026-06-23T19:17:07Z"
}
}