Home/CVE/Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4
CVE

CVE-2026-42246

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4

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.

HIGH · CVSS 7.4 EPSS 0.00016
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-392Missing Report of Error Condition
CWE-393Return of Wrong Status Code
CWE-636Not Failing Securely ('Failing Open')
CWE-754Improper Check for Unusual or Exceptional Conditions
CWE-841Improper Enforcement of Behavioral Workflow
▤

Affected Products & Versions

4
ruby-lang net\< 0.3.10
ruby-lang net\>= 0.4.0 and < 0.4.24
ruby-lang net\>= 0.5.0 and < 0.5.14
ruby-lang net\>= 0.6.0 and < 0.6.4
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems net-imap HIGH fixed in 0.6.4
▣

Scoring & Timeline

7.4
HIGH · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD09 May 2026 · 08:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
msrcCVE-2026-42246
🔗

References & Sources

8
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618Patch
https://github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485ePatch
https://github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42cPatch
https://github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873daPatch
https://github.com/ruby/net-imap/releases/tag/v0.3.10Release Notes
https://github.com/ruby/net-imap/releases/tag/v0.4.24Release Notes
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