High 7.6Published May 9, 2026

CVE-2026-42246net-imap vulnerable to STARTTLS stripping via invalid response timing

Updated under an hour ago (Oct 27, 2026, 5:10 PM ET)

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It affects ruby net-imap and 12 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for ruby net-imap

Exploited in the last 30 days

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: 7.6 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-392, CWE-393, CWE-754, CWE-636, CWE-841, CWE-325
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Aug 24, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

ruby net-imap ruby:net_imap (from the name)	before 0.3.10; from 0.4.0, < 0.4.24; from 0.5.0, < 0.5.14; from 0.6.0, < 0.6.4	CNA record
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux	from 0:4.0.3-35.el10_2 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support redhat:enterprise_linux_eus	from 0:3.3.10-11.el10_0.2 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support redhat:rhel_els	from 0:2.0.0.648-39.el7_9.1 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support redhat:rhel_aus	from 8040020260630124058.522a0ee4 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On redhat:rhel_eus_long_life	from 8040020260630124058.522a0ee4 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service redhat:rhel_tus	from 8080020260625114827.63b34585 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions redhat:rhel_e4s	from 8080020260625114827.63b34585 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support redhat:rhel_eus	from 0:3.0.7-165.el9_6.1 not affected	CISA ADP
Red Hat Red Hat Hardened Images redhat:hummingbird	from 4.0.0-33.4.hum1 not affected	CISA ADP
1–10 of 13

References

References

https://github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp	x-refsource-confirm, mitigation, vendor-advisory
https://github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618	x-refsource-misc, patch
https://github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e	x-refsource-misc, patch
https://github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c	x-refsource-misc, patch
https://github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da	x-refsource-misc, patch
https://github.com/ruby/net-imap/releases/tag/v0.3.10	x-refsource-misc, release-notes
https://github.com/ruby/net-imap/releases/tag/v0.4.24	x-refsource-misc, release-notes
https://github.com/ruby/net-imap/releases/tag/v0.5.14	x-refsource-misc, release-notes
https://access.redhat.com/errata/RHSA-2026:33462
https://access.redhat.com/errata/RHSA-2026:33512
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.