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commons-email only checks the certificate chain by default, so any valid certificate was accepted regardless of host. Enable server identity checking wherever SSL or STARTTLS is configured. Signed-off-by: Nico Piel <nico.piel@hotmail.de>
NicoPiel
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gibson9583,
jonbartels,
kayyagari,
kpalang,
mgaffigan,
ssrowe and
tonygermano
October 28, 2026 13:53
mgaffigan
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Oct 28, 2026
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This would be exploitable with MITM. Probably needs a CVE filed.
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What
Calls
email.setSSLCheckServerIdentity(true)wherever SMTP is set up with SSL or STARTTLS:DefaultSmtpConfiguration(SMTP Sender connector)DefaultConfigurationController(server email settings / test email)ServerSMTPConnectionWhy
SonarQube flags these as
java:S5527(6 critical issues). By default commons-email checks the certificate chain but never matches the certificate to the host. So anyone in the network path with any valid certificate could intercept SMTP traffic, including the login credentials.Reviewer notes
./gradlew :server:compileJavaon JDK 17. No automated tests cover these paths, and I haven't tested it against a real TLS mail server.🤖 Generated with Claude Code