CVE-2026-42246

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure, data tampering.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-09 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-24 13:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 7.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-05-09 20:16 UTC

Last modified

2026-08-24 13:18 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-392

Record status

Modified

Affected

• ruby-lang net\ < 0.3.10
• ruby-lang net\ < 0.4.24
• ruby-lang net\ < 0.5.14
• ruby-lang net\ < 0.6.4

Attack profile CVSS 4.0 · 7.6

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

None

User interaction

Passive

Confidentiality

High

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-42246.md and follow it. Check whether this project is affected by CVE-2026-42246. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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