CVE-2026-42246

HIGHNVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.4 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.4
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.4Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
7.4
EG Score
7.4(medium)
EPSS
24.4%
KEV
Not listed

Published

May 9, 2026

Last Modified

July 6, 2026

Advisory Details (8)

Auto-updated May 18, 2026
Patch available. Sources: github.
github Patch Available

STARTTLS stripping via invalid response timing · Advisory · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp
generic

Release v0.5.14 · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/releases/tag/v0.5.14
generic

Release v0.4.24 · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/releases/tag/v0.4.24
generic

Release v0.3.10 · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/releases/tag/v0.3.10
generic

🔀 Merge pull request #665 from ruby/backport/v0.5/STARTTLS-stripping · ruby/net-imap@f79d35b · GitHub

https://github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da
generic

🔀 Merge pull request #667 from ruby/backport/v0.3/STARTTLS-stripping · ruby/net-imap@97e2488 · GitHub

https://github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c
generic

🔀 Merge pull request #666 from ruby/backport/v0.4/STARTTLS-stripping · ruby/net-imap@24a4e77 · GitHub

https://github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e
generic

🔀 Merge pull request #664 from ruby/security/STARTTLS-stripping · ruby/net-imap@0ede4c4 · GitHub

https://github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618

Vendor Advisories for CVE-2026-42246(17)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubunturuby2.3-tcltk (2.3.1-2~ubuntu16.04.16+esm14) @ xenial2026-06-28ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
net-imap0.1.0 ... 0.3.9 (19 versions)0.3.10—

Weakness Classification(6)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 65× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 109 total refreshes for this CVE.

  1. 2026-07-06 16:27 UTCEPSS rescore
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  12. 2026-06-28 03:43 UTCEG score recompute
  13. 2026-06-28 03:43 UTCVendor advisory
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  15. 2026-06-27 10:31 UTCVendor advisory
  16. 2026-06-27 03:08 UTCEPSS rescore
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  19. 2026-06-26 05:46 UTCVendor advisory
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  1. 2026-06-21 14:56 UTCEPSS rescore
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  8. 2026-06-17 01:14 UTCEG score recompute
  9. 2026-06-17 01:14 UTCVendor advisory
  10. 2026-06-16 17:52 UTCEPSS rescore
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  12. 2026-06-16 07:50 UTCVendor advisory
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  40. 2026-06-07 12:01 UTCEG score recompute
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Frequently asked(5)

What is CVE-2026-42246?
CVE-2026-42246 is a high vulnerability published on May 9, 2026. 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,…
When was CVE-2026-42246 disclosed?
CVE-2026-42246 was first published in the National Vulnerability Database on May 9, 2026, with the most recent update on July 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42246 actively exploited?
CVE-2026-42246 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 24.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42246?
CVE-2026-42246 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2026-42246?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42246, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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