Trim trailing dot from trusted IMDS hostnames#301
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DNS resolvers may return hostnames with a trailing dot (FQDN form), e.g. `metadata.google.internal.`. The previous equality check failed to match these, risking false-positive stored-SSRF blocks for GCP IMDS. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Create helpers/net/NormalizeHostname.java (lowercase, strip trailing dot, IDN via java.net.IDN) to give SSRF code a canonical hostname form. Replace the inline normalization in TrustedHosts.isTrustedHostname with a call to this helper. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
tomaisthorpe
approved these changes
Jun 8, 2026
kapytein
reviewed
Jun 10, 2026
| String lower = hostname.toLowerCase(); | ||
| String noDot = lower.endsWith(".") ? lower.substring(0, lower.length() - 1) : lower; | ||
| try { | ||
| return IDN.toUnicode(noDot); |
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why do we need this? if a DNS request is made to a host with punycode, it isn't converted to unicode by java's getallbyname
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Summary
DNS resolvers sometimes return fully-qualified domain names with a trailing dot (e.g.
metadata.google.internal.). The previousArrays.asList(trustedHosts).contains(hostname)check inTrustedHosts.isTrustedHostnamedid not normalize the hostname, so trailing-dot forms were not matched and GCP IMDS requests could be incorrectly flagged as stored SSRF.ResolverTestThis is the same fix already applied in firewall-go (PR #459). Ported to Python, Ruby, .NET, PHP, and Java.
Test plan
./gradlew :agent_api:test --tests "vulnerabilities.ssrf.ResolverTest"passesSummary by Aikido
🐛 Bugfixes
🔧 Refactors
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