CVE-2026-42246 (GCVE-0-2026-42246)

Vulnerability from cvelistv5 – Published: 2026-05-09 19:33 – Updated: 2026-07-01 12:04
VLAI
Title
net-imap vulnerable to STARTTLS stripping via invalid response timing
Summary
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.
Severity
7.6 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
  • CWE-392 - Missing Report of Error Condition
  • CWE-393 - Return of Wrong Status Code
  • CWE-754 - Improper Check for Unusual or Exceptional Conditions
  • CWE-636 - Not Failing Securely ('Failing Open')
  • CWE-841 - Improper Enforcement of Behavioral Workflow
  • CWE-325 - Missing Cryptographic Step
Assigner
References
URL Tags
https://github.com/ruby/net-imap/security/advisor… x_refsource_CONFIRM
https://github.com/ruby/net-imap/commit/0ede4c40b… x_refsource_MISC
https://github.com/ruby/net-imap/commit/24a4e770b… x_refsource_MISC
https://github.com/ruby/net-imap/commit/97e2488fb… x_refsource_MISC
https://github.com/ruby/net-imap/commit/f79d35bf5… x_refsource_MISC
https://github.com/ruby/net-imap/releases/tag/v0.3.10 x_refsource_MISC
https://github.com/ruby/net-imap/releases/tag/v0.4.24 x_refsource_MISC
https://github.com/ruby/net-imap/releases/tag/v0.5.14 x_refsource_MISC
https://access.redhat.com/security/cve/CVE-2026-42246 vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2468499 issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v… x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:33565 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33540 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33514 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33515 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33630 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33462 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33512 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33576 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33577 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33721 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33552 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:33551 vendor-advisoryx_refsource_REDHAT
Impacted products
Vendor Product Version
ruby net-imap Affected: < 0.3.10
Affected: >= 0.4.0, < 0.4.24
Affected: >= 0.5.0, < 0.5.14
Affected: >= 0.6.0, < 0.6.4
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Red Hat Red Hat Enterprise Linux AppStream (v. 10)     cpe:/o:redhat:enterprise_linux:10.2
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Red Hat Red Hat Enterprise Linux AppStream (v. 8)     cpe:/a:redhat:enterprise_linux:8::appstream
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Red Hat Red Hat Enterprise Linux AppStream E4S (v.9.4)     cpe:/a:redhat:rhel_e4s:9.4::appstream
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Red Hat Red Hat Enterprise Linux AppStream EUS (v.9.6)     cpe:/a:redhat:rhel_eus:9.6::appstream
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Red Hat Red Hat Enterprise Linux AppStream (v. 9)     cpe:/a:redhat:enterprise_linux:9::appstream
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Red Hat Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)     cpe:/o:redhat:enterprise_linux:10.2
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Red Hat Red Hat CodeReady Linux Builder EUS (v.9.6)     cpe:/a:redhat:rhel_eus:9.6::crb
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Red Hat Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)     cpe:/a:redhat:enterprise_linux:9::crb
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Red Hat Red Hat Hardened Images     cpe:/a:redhat:hummingbird:1
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Red Hat Red Hat Enterprise Linux 6     cpe:/o:redhat:enterprise_linux:6
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Red Hat Red Hat Enterprise Linux 7     cpe:/o:redhat:enterprise_linux:7
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Red Hat Red Hat OpenShift Container Platform 4     cpe:/a:redhat:openshift:4
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Red Hat Red Hat 3scale API Management Platform 2     cpe:/a:redhat:red_hat_3scale_amp:2
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      "date": "2026-07-01",
      "epss": "0.00312",
      "percentile": "0.23052"
    },
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    "vulnrichment": {
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      "dataType": "CVE_RECORD",
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    }
  }
}


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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.