CVE-2026-53753
CRITICALEPSS 86th pctlDescription
Crawl4AI is an open-source LLM friendly web crawler & scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Elevated risk: more likely to be exploited than 86% of all known CVEs.
References
Related Vulnerabilities
Other CWE-94 (Code Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-9841 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2015-1635 | Critical | 9.8 | 100% | KEV | - |
| CVE-2022-22954 | Critical | 9.8 | 100% | KEV + Ransom | - |
| CVE-2025-3248 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2025-49704 | High | 8.8 | 100% | KEV + Ransom | Fix |
| CVE-2021-22204 | Medium | 6.8 | 100% | KEV | Fix |
Common questions
How do I fix CVE-2026-53753?
Upgrade crawl4ai to 0.8.7 or later.
Is CVE-2026-53753 being actively exploited?
Not that we know of. CVE-2026-53753 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 86% of all scored CVEs.
How severe is CVE-2026-53753?
CVE-2026-53753 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-53753 affect?
Published advisories record a fix for crawl4ai (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-53753
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-29.