CVE-2026-42246: net-imap vulnerable to STARTTLS stripping via invalid response timing
(updated )
A man-in-the-middle attacker can cause Net::IMAP#starttls to return “successfully”, without starting TLS.
References
- github.com/advisories/GHSA-vcgp-9326-pqcp
- github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618
- github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e
- github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c
- github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da
- github.com/ruby/net-imap/releases/tag/v0.3.10
- github.com/ruby/net-imap/releases/tag/v0.4.24
- github.com/ruby/net-imap/releases/tag/v0.5.14
- github.com/ruby/net-imap/releases/tag/v0.6.4
- github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp
- github.com/rubysec/ruby-advisory-db/blob/master/gems/net-imap/CVE-2026-42246.yml
- nostarttls.secvuln.info/
- nvd.nist.gov/vuln/detail/CVE-2026-42246
- www.rfc-editor.org/info/rfc8314
Code Behaviors & Features
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