CVE-2026-42246: CWE-392: Missing Report of Error Condition in ruby net-imap
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.
AI Analysis
Technical Summary
The net-imap Ruby library implements IMAP client functionality. Versions before 0.3.10, 0.4.24, 0.5.14, and 0.6.4 contain a vulnerability where the starttls method can return a successful status without initiating TLS encryption, due to missing error reporting (CWE-392). This flaw enables a man-in-the-middle attacker to intercept communications that are expected to be encrypted. The vulnerability is fixed in the mentioned versions.
Potential Impact
An attacker positioned as a man-in-the-middle can cause the net-imap client to believe TLS encryption has started when it has not, potentially exposing sensitive email data transmitted over the network. This undermines confidentiality and integrity of the communication channel. No known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade net-imap to version 0.3.10, 0.4.24, 0.5.14, or 0.6.4 or later, where this vulnerability has been patched. Patch status is confirmed by the version fixes noted in the advisory. No additional mitigations are indicated.
CVE-2026-42246: CWE-392: Missing Report of Error Condition in ruby net-imap
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.
CVSS v4.0
Score 7.6high
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The net-imap Ruby library implements IMAP client functionality. Versions before 0.3.10, 0.4.24, 0.5.14, and 0.6.4 contain a vulnerability where the starttls method can return a successful status without initiating TLS encryption, due to missing error reporting (CWE-392). This flaw enables a man-in-the-middle attacker to intercept communications that are expected to be encrypted. The vulnerability is fixed in the mentioned versions.
Potential Impact
An attacker positioned as a man-in-the-middle can cause the net-imap client to believe TLS encryption has started when it has not, potentially exposing sensitive email data transmitted over the network. This undermines confidentiality and integrity of the communication channel. No known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade net-imap to version 0.3.10, 0.4.24, 0.5.14, or 0.6.4 or later, where this vulnerability has been patched. Patch status is confirmed by the version fixes noted in the advisory. No additional mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-25T05:37:12.118Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69ff93c0cbff5d86106e4582
Added to database: 05/09/2026, 20:06:24 UTC
Last enriched: 05/17/2026, 10:08:28 UTC
Last updated: 06/28/2026, 08:51:25 UTC
Views: 191
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