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HIGH

CVE-2026-42246

CVE-2026-42246 — net-imap vulnerable to STARTTLS stripping via invalid response timing

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.

Published Updated Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

ruby

19 products listed

CVSS base

7.4

HIGH

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (2)

rubyredhat

Products (19)

net imapred hat enterprise linux 10red hat enterprise linux 10 0 extended update supportred hat enterprise linux 7 extended lifecycle supportred hat enterprise linux 8red hat enterprise linux 8 4 advanced mission critical update supportred hat enterprise linux 8 4 extended update support long life add onred hat enterprise linux 8 6 advanced mission critical update supportred hat enterprise linux 8 6 extended update support long life add onred hat enterprise linux 8 8 telecommunications update servicered hat enterprise linux 8 8 update services for sap solutionsred hat enterprise linux 9red hat enterprise linux 9 2 update services for sap solutionsred hat enterprise linux 9 4 update services for sap solutionsred hat enterprise linux 9 6 extended update supportred hat hardened imagesred hat 3scale api management platform 2red hat enterprise linux 6red hat openshift container platform 4

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
7.4CVSS 3.1HIGH——cvelistV5

Weakness & attack patterns

  • CWE-392
  • CWE-393
  • CWE-754
  • CWE-636
  • CWE-841
  • CWE-325

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1553.002Subvert Trust Controls: Code Signing

References

25 on the record

Elsewhere on this site

  • rubyevery CVE for this vendor
  • redhatevery CVE for this vendor
  • CWE-392other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.