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 v4 7.6
EPSS 0.0005
EPSS Percentile 15.5%
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 (4)
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
Published May 09, 2026
Tracked Since May 10, 2026