CVE-2026-77866
Server-Side Request Forgery (SSRF) vulnerability in Slab safeurl allows an attacker who controls a validated URL to reach internal network destinations the library is configured to block.
Overview
CVE-2026-77866 is a known-severity vulnerability. It was published on September 15, 2026.
Technical description
Server-Side Request Forgery (SSRF) vulnerability in Slab safeurl allows an attacker who controls a validated URL to reach internal network destinations the library is configured to block.
Only IPv4 addresses are matched against the reserved ranges and the blocklist. Every other address is treated as matching nothing, so a destination that is rejected in its IPv4 form is accepted when written as an IPv6 address, IPv6 entries in the blocklist never match, and a host that resolves to no IPv4 address is accepted regardless of where it points. Deployments that rely on the allowlist instead are unaffected, because there an unmatched address is rejected.
This issue affects safeurl: from 0.1.0 onward.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-77866?
CVE-2026-77866 is a known-severity vulnerability. It was published on September 15, 2026.
How severe is CVE-2026-77866?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-77866?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-77866?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-77866 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.