Details
It was discovered that Ruby's Net::IMAP library did not properly verify
that Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote
attacker could possibly use this issue to perform a machine-in-the-middle attack and silently
bypass TLS encryption. (CVE-2026-42246)
It was also discovered that Ruby's Net::IMAP library did not validate
string arguments passed to certain commands. A remote attacker could possibly use this issue to
inject arbitrary IMAP commands. (CVE-2026-42257)
It was discovered that Ruby's Net::IMAP library did not properly verify
that Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote
attacker could possibly use this issue to perform a machine-in-the-middle attack and silently
bypass TLS encryption. (CVE-2026-42246)
It was also discovered that Ruby's Net::IMAP library did not validate
string arguments passed to certain commands. A remote attacker could possibly use this issue to
inject arbitrary IMAP commands. (CVE-2026-42257)
Update instructions
In general, a standard system update will make all the necessary changes.
Learn more about how to get the fixes.The problem can be corrected by updating your system to the following package versions:
| Ubuntu Release | Package Version | ||
|---|---|---|---|
| 18.04 LTS bionic | libruby2.5 – 2.5.1-1ubuntu1.16+esm8 | ||
| ruby2.5 – 2.5.1-1ubuntu1.16+esm8 | |||
| 16.04 LTS xenial | libruby2.3 – 2.3.1-2~ubuntu16.04.16+esm14 | ||
| ruby2.3 – 2.3.1-2~ubuntu16.04.16+esm14 | |||
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