CVE-2026-42246

CVE-2026-42246 is a high-severity vulnerability in Ruby-lang Net with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-392.

Key facts

Description

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.

Frequently asked questions

What is CVE-2026-42246?
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.
How severe is CVE-2026-42246?
CVE-2026-42246 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-42246 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42246?
CVE-2026-42246 affects Ruby-lang Net. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42246?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42246 have an EU (EUVD) identifier?
Yes. CVE-2026-42246 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28924.
When was CVE-2026-42246 published?
CVE-2026-42246 was published on 2026-05-09 and last updated on 2026-07-07.

References

Affected products (1)

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