Vulnerability in Ruby Net-Imap
CVE-2026-42245
Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.007 (52.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.007 · change: +0.003
Affected products
- Ruby Net-Imap — versions < 0.4.24, >= 0.5.0, < 0.5.14, >= 0.6.0, < 0.6.4
- Ruby-Lang Net\ — versions \
- Ruby-Lang Net\:\:imap
Weakness classification (CWE)
References
- github.com/ruby/net-imap/security/advisories/GHSA-q2mw-fvj9-vvcw (Mitigation, Vendor Advisory)
- github.com/ruby/net-imap/commit/6091f7d6b1f3514cafbfe39c76f2b5d73de3ca96 (Patch)
- github.com/ruby/net-imap/commit/88d95231fc8afef11c1f074453f7d75b68c9dfda (Patch)
- github.com/ruby/net-imap/commit/de685f91a4a4cc75eb80da898c2bf8af08d34819 (Patch)
- github.com/ruby/net-imap/releases/tag/v0.4.24 (Release Notes)
- github.com/ruby/net-imap/releases/tag/v0.5.14 (Release Notes)
- github.com/ruby/net-imap/releases/tag/v0.6.4 (Release Notes)
Frequently asked questions
- What is CVE-2026-42245?
- CVE-2026-42245 is a high-severity vulnerability in Ruby Net-Imap, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-05-09.
- How severe is CVE-2026-42245?
- High severity. CVSS v3 base score is 7.5 out of 10.