Vulnerability Report

CVE-2026-42246

Title: MITM bypasses TLS initiation

Other

Proof Of Concept

No public PoC currently indexed for CVE-2026-42246.

CWE Category CWE-392
Published Date May 09, 2026
Modified Date May 18, 2026
Exploit Status Not Found
Score 7.6 CVSS v4.0
Exploit Probability (EPSS)
0.02%

Vulnerability Summary

CVE-2026-42246: 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.

Impacted Vendors

N
net-dns 1
R
ruby-lang 1

Reference Links

https://github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618 https://github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e https://github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c https://github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da https://github.com/ruby/net-imap/releases/tag/v0.3.10 https://github.com/ruby/net-imap/releases/tag/v0.4.24 https://github.com/ruby/net-imap/releases/tag/v0.5.14 https://github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp
CVSS v4.0
Source Entity [email protected]
Severity HIGH
7.6
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
PASSIVE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
N/A
RAW VECTOR 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
CVSS v3.1
Source Entity [email protected]
Severity HIGH
7.4
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-42246 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction PASSIVE
CVSS Vector String 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

Affected Stack

No specific products linked.