CVE-2026-42246

HIGH

net-imap vulnerable to STARTTLS stripping via invalid response timing

Title source: cna
STIX 2.1

Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4, a man-in-the-middle attacker can cause Net::IMAP#starttls to return "successfully", without starting TLS. This issue has been patched in versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4.

References (8)

Core 8
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/ruby/net-imap/releases/tag/v0.3.10
X_Refsource_Misc x_refsource_misc
https://github.com/ruby/net-imap/releases/tag/v0.4.24
X_Refsource_Misc x_refsource_misc
https://github.com/ruby/net-imap/releases/tag/v0.5.14

Scores

CVSS v3 7.4
EPSS 0.0042
EPSS Percentile 33.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-392 CWE-393 CWE-636 CWE-754 CWE-841
Status published
Products (9)
ruby/net-imap < 0.3.10
ruby/net-imap >= 0.4.0, < 0.4.24
ruby/net-imap >= 0.5.0, < 0.5.14
ruby/net-imap >= 0.6.0, < 0.6.4
ruby-lang/net\ < 0.3.10
rubygems/net-imap 0 - 0.3.10RubyGems
rubygems/net-imap 0.4.0 - 0.4.24RubyGems
rubygems/net-imap 0.5.0 - 0.5.14RubyGems
rubygems/net-imap 0.6.0 - 0.6.4RubyGems
Published May 09, 2026
Tracked Since May 10, 2026