Bug 2468499 (CVE-2026-42246)

Summary: CVE-2026-42246 net-imap: ruby: Net::IMAP: Information disclosure via man-in-the-middle attack bypassing TLS
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akostadi, amasferr, dmayorov, eshamard, jkoehler, jlledo, jvasik, kaycoth, lphiri, pantinor, rblanco, rhel-process-autobot, sdawley, tsedmik, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Ruby net-imap library. When upgrading a cleartext IMAP connection to TLS using the Net::IMAP#starttls method, the library improperly handles certain responses received during STARTTLS negotiation. A man-in-the-middle (MITM) attacker can inject a predicted tagged OK response before the client completes the STARTTLS command, causing the operation to appear successful without establishing a TLS session. As a result, the connection may continue to transmit sensitive information in cleartext and enable modification of data exchanged over the affected connection, while the application incorrectly believes that encryption has been enabled.
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Clone Of: Environment:
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2492090    
Bug Blocks:    

Description OSIDB Bzimport 2026-05-09 20:01:28 UTC
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.

Comment 5 errata-xmlrpc 2026-06-30 10:49:28 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:33462 https://access.redhat.com/errata/RHSA-2026:33462

Comment 6 errata-xmlrpc 2026-06-30 15:26:37 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:33514 https://access.redhat.com/errata/RHSA-2026:33514

Comment 7 errata-xmlrpc 2026-06-30 15:28:36 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:33540 https://access.redhat.com/errata/RHSA-2026:33540

Comment 8 errata-xmlrpc 2026-06-30 15:35:59 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:33512 https://access.redhat.com/errata/RHSA-2026:33512

Comment 9 errata-xmlrpc 2026-06-30 16:05:47 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:33565 https://access.redhat.com/errata/RHSA-2026:33565

Comment 10 errata-xmlrpc 2026-06-30 16:11:25 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:33515 https://access.redhat.com/errata/RHSA-2026:33515

Comment 11 errata-xmlrpc 2026-06-30 17:07:46 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:33630 https://access.redhat.com/errata/RHSA-2026:33630

Comment 12 errata-xmlrpc 2026-06-30 17:12:37 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:33576 https://access.redhat.com/errata/RHSA-2026:33576

Comment 13 errata-xmlrpc 2026-06-30 18:13:31 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:33577 https://access.redhat.com/errata/RHSA-2026:33577

Comment 14 errata-xmlrpc 2026-07-01 08:17:06 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:34076 https://access.redhat.com/errata/RHSA-2026:34076

Comment 15 errata-xmlrpc 2026-07-06 03:42:11 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:35834 https://access.redhat.com/errata/RHSA-2026:35834

Comment 16 errata-xmlrpc 2026-07-06 06:35:28 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:35866 https://access.redhat.com/errata/RHSA-2026:35866

Comment 17 errata-xmlrpc 2026-07-06 06:38:53 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:35867 https://access.redhat.com/errata/RHSA-2026:35867

Comment 18 errata-xmlrpc 2026-07-06 13:58:04 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:35895 https://access.redhat.com/errata/RHSA-2026:35895

Comment 19 errata-xmlrpc 2026-07-07 06:47:55 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:36099 https://access.redhat.com/errata/RHSA-2026:36099