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CVE-2026-42246

HIGHCVSS 7.4/10EPSS 0.31%

Last modified

CVE-2026-42246 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. 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. EPSS estimates a 0.31% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.4/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS 4.0
7.6/10

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.31%

23.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
Ruby-LangNet\< 0.3.10Imap
Ruby-LangNet\>= 0.4.0, < 0.4.24Imap
Ruby-LangNet\>= 0.5.0, < 0.5.14Imap
Ruby-LangNet\>= 0.6.0, < 0.6.4Imap

References

Timeline

Published
Last Modified
Status
Modified

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 score of 7.4/10 (HIGH severity). The EPSS model estimates a 0.31% probability of exploitation in the next 30 days.
How do I fix CVE-2026-42246?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST