Open Notebook URL Validation Bypass Enables SSRF Attacks

Open Notebook before 1.11.0 fails to validate the URL parameter in POST /api/sources endpoint, allowing authenticated users to perform server-side requests to internal services. Attackers can supply arbitrary URLs to read cloud metadata, internal network services, and localhost-bound services through the application server's direct HTTP requests.

Casky was already ahead

This CVE exploits attack patterns that Casky's 331matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-90769 is a Server-Side Request Forgery (SSRF) vulnerability in Open Notebook versions before 1.11.0 that stems from insufficient URL validation on the POST /api/sources endpoint. Authenticated attackers can exploit this flaw to make arbitrary HTTP requests from the application server, potentially accessing sensitive cloud metadata (AWS/Azure/GCP credentials), internal microservices, localhost-bound services, and other backend systems that are not exposed to the internet. This vulnerability matters because SSRF attacks often serve as a pivot point for lateral movement, credential theft, and further compromise of internal infrastructure—particularly dangerous in cloud-native environments where instance metadata services are commonly exploited.

Casky's 331 matching skills leverage Claude's extended reasoning to detect the attack patterns underlying this vulnerability across MITRE ATT&CK techniques TA0001 (Initial Access) and TA0006 (Credential Access). Practitioners using Casky would observe detections for CWE-918 violations when analyzing POST requests to /api/sources with suspicious URL parameters targeting internal IP ranges (10.0.0.0/8, 169.254.169.254), localhost addresses, or metadata service endpoints. The platform's skills would correlate evidence of URL parameter manipulation with downstream HTTP requests originating from the application server to internal services, flagging the reconnaissance and credential harvesting patterns that typically follow successful SSRF exploitation—enabling defenders to identify and remediate compromised instances before attackers extract sensitive credentials or configuration data.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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331 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-90769.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0006

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