Fix uppercase-scheme bypass in LLM tool-input guard#13
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JsonToolInputGuard.looksLikeUrl matched http:// and https:// prefixes case-sensitively, so a tool-input URL with an uppercase scheme (HTTP://169.254.169.254/, HtTpS://evil.com/) was never collected as a candidate and skipped policy validation entirely, bypassing the host allowlist and IP-literal checks. URI schemes are case-insensitive (RFC 3986 3.1) and the downstream scheme check already used equalsIgnoreCase, so the case-sensitive match in the collection step was an unintended inconsistency. Lower-case before the prefix test. Adds regression tests for uppercase/mixed-case blocked URLs and confirms an uppercase whitelisted URL still passes. Affects ssrf-guard-springai and ssrf-guard-langchain4j, which both route tool input through this guard. Same class of bug fixed in the JS sibling ssrf-guard-js.
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Security fix
JsonToolInputGuard.looksLikeUrlcollected candidate URLs with a case-sensitivehttp:///https://prefix test:A tool-input URL with an uppercase scheme (
HTTP://169.254.169.254/…,HtTpS://evil.com/) was never collected as a candidate, so it skipped policy validation entirely — bypassing the host allowlist and IP-literal checks. URI schemes are case-insensitive (RFC 3986 §3.1) and the downstream scheme check already usedequalsIgnoreCase, so the case-sensitive collection step was an unintended inconsistency. Detection is now case-insensitive.Blast radius
JsonToolInputGuardis the single tool-input scanner; bothssrf-guard-springaiandssrf-guard-langchain4jroute tool input through it, so both LLM-framework adapters were affected.Changes
JsonToolInputGuard.looksLikeUrlHTTP://metadata URL and mixed-caseHtTpS://nested URL blocked; uppercaseHTTPS://whitelisted URL still passesdocs/changelog.md+ root mirror) under[Unreleased]→ SecurityVerification
Full CI-equivalent build green locally:
./gradlew build jacocoTestReport→ BUILD SUCCESSFUL, all module tests pass.Context
Same bug found and fixed in the JS sibling
ssrf-guard-js(shipped in@devslab/ssrf-guard-js@0.1.2). Suggest a v3.1.1 patch release after merge.보안 수정 (한국어)
looksLikeUrl가 URL 수집을 대소문자 구분으로 해서 대문자 스킴 URL(HTTP://…)이 정책 검증을 건너뛰던 우회를 수정. 스킴은 대소문자 무시(RFC 3986)이고 다음 코드가 이미equalsIgnoreCase를 쓰므로 수집 단계만 case-sensitive였던 불일치. springai·langchain4j 둘 다 영향. 로컬 전체 빌드 green. JS 형제와 동일 버그 → 머지 후 v3.1.1 권장.