Vulnerability in Ruby Net-Imap
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (22.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Ruby Net-Imap — versions < 0.3.10, >= 0.4.0, < 0.4.24, >= 0.5.0, < 0.5.14
- Ruby-Lang Net\ — versions \
- Ruby-Lang Net\:\:imap
Weakness classification (CWE)
References
- github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp (Mitigation, Vendor Advisory)
- github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618 (Patch)
- github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e (Patch)
- github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c (Patch)
- github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da (Patch)
- github.com/ruby/net-imap/releases/tag/v0.3.10 (Release Notes)
- github.com/ruby/net-imap/releases/tag/v0.4.24 (Release Notes)
- github.com/ruby/net-imap/releases/tag/v0.5.14 (Release Notes)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-42246?
- CVE-2026-42246 is a high-severity vulnerability in Ruby Net-Imap, classified under CWE-392. CVSS score: 7.4/10. Published 2026-05-09.
- How severe is CVE-2026-42246?
- High severity. CVSS v3 base score is 7.4 out of 10.