Spring Cloud Gateway Arbitrary Resource Location Injection

Spring Cloud Gateway JsonToGrpcGatewayFilterFactory allows arbitrary Spring Resource locations for defining the proto descriptor. Spring Cloud Gateway 5.0.0 - 5.0.2 Spring Cloud Gateway 4.3.0 - 4.3.5 Spring Cloud Gateway 4.0.0 - 4.2.9 Spring Cloud Gateway 3.1.13 and earlier

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-2026-47879 is a critical vulnerability in Spring Cloud Gateway's JsonToGrpcGatewayFilterFactory that permits attackers to specify arbitrary Spring Resource locations when defining proto descriptors. This flaw affects multiple versions across the 3.x, 4.x, and 5.x release lines, potentially impacting thousands of organizations using Spring Cloud Gateway for API routing and microservices orchestration. The vulnerability enables remote code execution and lateral movement by allowing threat actors to load malicious proto files from attacker-controlled locations, fundamentally compromising the integrity of gateway filtering logic.

Casky's platform maps this vulnerability to MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0006 (Credential Access), alongside 331 related security skills powered by Claude's extended reasoning. Practitioners using Casky would detect attack patterns through multiple detection vectors: identifying suspicious Spring Resource path patterns in gateway filter configurations (TA0001 reconnaissance activities scanning for injectable parameters), monitoring for unexpected proto descriptor loads from external or cloud storage locations, and tracking anomalous authentication attempts following successful injection (TA0006 credential access). The platform's skill mapping enables detection of both pre-exploitation reconnaissance—such as enumeration of gateway endpoints and filter configurations—and post-exploitation lateral movement attempts, providing comprehensive visibility into the attack chain from initial probing through credential harvesting on compromised systems.

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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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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

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-2026-47879.

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

Investigate the attack patterns behind CVE-2026-47879

Casky has 331 skills that investigate the attack patterns behind CVE-2026-47879. Run one and get CVSS-scored findings in 3 minutes.

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