Review reviewHigh

CVE-2026-42246

ruby net-imap, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support

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.

CVSS: 7.6
EPSS: 0.31%
CISA KEV: Not listed
Published: 2026.05.10

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.31%

Technical severityCVSS 7.6

Vulnerability overview

Affected product and versions

Product: ruby net-imap, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support
Affected versions: >= < 0.3.10, >= >= 0.4.0, < 0.4.24, >= >= 0.5.0, < 0.5.14, >= >= 0.6.0, < 0.6.4, < 0.3.10, >= 0.4.0 < 0.4.24, >= 0.5.0 < 0.5.14, >= 0.6.0 < 0.6.4
Fixed versions: 0.3.10, 0.4.24, 0.5.14, 0.6.4

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that ruby net-imap, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS 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
CWE: CWE-325, CWE-392, CWE-393, CWE-636, CWE-754, CWE-841