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.
CVE-2026-42245
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- 34(Track)EG Risk 34/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity75% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 34%
- KEV
- Not listed
Published
May 9, 2026
Last Modified
July 24, 2026
Advisory Details (7)
Auto-updated May 18, 2026Quadratic complexity when reading response literals · Advisory · ruby/net-imap · GitHub
https://github.com/ruby/net-imap/security/advisories/GHSA-q2mw-fvj9-vvcwRelease v0.5.14 · ruby/net-imap · GitHub
https://github.com/ruby/net-imap/releases/tag/v0.5.14Release v0.4.24 · ruby/net-imap · GitHub
https://github.com/ruby/net-imap/releases/tag/v0.4.24🔀 Merge pull request #642 from ruby/response_reader-performance · ruby/net-imap@de685f9 · GitHub
https://github.com/ruby/net-imap/commit/de685f91a4a4cc75eb80da898c2bf8af08d34819🔀 Merge pull request #651 from ruby/backport/v0.4/response_reader-non… · ruby/net-imap@88d9523 · GitHub
https://github.com/ruby/net-imap/commit/88d95231fc8afef11c1f074453f7d75b68c9dfda🔀 Merge pull request #650 from ruby/backport/v0.5/response_reader-non… · ruby/net-imap@6091f7d · GitHub
https://github.com/ruby/net-imap/commit/6091f7d6b1f3514cafbfe39c76f2b5d73de3ca96Vendor Advisories for CVE-2026-42245(12)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:38694Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
- RHSA-2026:37238Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:3.3 security update
- RHSA-2026:36099Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:3.3 security update
- RHSA-2026:35895Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby security update
- RHSA-2026:33721Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
- RHSA-2026:33577Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:4.0 security update
- RHSA-2026:33576Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:3.3 security update
- RHSA-2026:33515Red Hat Product SecurityHigh
Red Hat Security Advisory: ruby:3.3 security update
- +4 more
Patch Availability(12)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| redhat | ruby3-4-main-3.4.10-31.hum1 | 2026-07-13 | redhat |
| redhat | ruby:3.3-9060020260630075016.9 | 2026-07-09 | redhat |
| redhat | ruby:3.3-9040020260630065449.9 | 2026-07-07 | redhat |
| redhat | ruby-0:3.3.10-11.el10_0.2 | 2026-07-06 | redhat |
| redhat | ruby:4.0-9080020260619130154.9 | 2026-06-30 | redhat |
| redhat | ruby4-0-main-4.0.0-33.4.hum1 | 2026-06-30 | redhat |
| redhat | ruby3-3-main-3.3.10-23.2.hum1 | 2026-06-30 | redhat |
| redhat | ruby-0:3.3.10-13.el10_2 | 2026-06-30 | redhat |
| redhat | ruby4.0-0:4.0.3-35.el10_2 | 2026-06-30 | redhat |
| redhat | ruby:3.3-8100020260615131010.489197e6 | 2026-06-30 | redhat |
| redhat | ruby:3.3-9080020260615131001.9 | 2026-06-30 | redhat |
| redhat | ruby3-4-main-3.4.8-31.2.hum1 | 2026-06-30 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
RubyGems(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| net-imap | 0.1.0 ... 0.4.9.1 (45 versions) | 0.4.24 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 11× in last 7d / 35× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-26 14:54 UTCEPSS rescore
- 2026-07-26 14:54 UTCEPSS rescore
- 2026-07-26 08:25 UTCEG score recompute
- 2026-07-26 08:25 UTCVendor advisory
- 2026-07-25 14:18 UTCEPSS rescore
- 2026-07-24 14:17 UTCEPSS rescore
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 03:11 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
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- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-16 03:53 UTCOSV refresh
- 2026-07-15 16:57 UTCEPSS rescore
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- 2026-07-13 22:30 UTCEPSS rescore
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- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-08 15:15 UTCEPSS rescore
- 2026-07-07 13:46 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
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- 2026-07-06 16:27 UTCEPSS rescore
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- 2026-06-25 13:49 UTCEPSS rescore
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- 2026-06-15 17:49 UTCEPSS rescore
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- 2026-06-08 14:17 UTCEPSS rescore
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- 2026-06-07 15:25 UTCEPSS rescore
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- 2026-06-06 13:47 UTCEPSS rescore
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- 2026-06-02 20:13 UTCEPSS rescore
- 2026-06-01 13:52 UTCEPSS rescore
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- 2026-05-31 22:30 UTCEPSS rescore
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- 2026-05-29 13:44 UTCEPSS rescore
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- 2026-05-20 22:38 UTCEPSS rescore
- 2026-05-20 22:38 UTCEPSS rescore
- 2026-05-20 13:27 UTCEG score recompute
- 2026-05-20 11:22 UTCEPSS rescore
- 2026-05-20 11:22 UTCEPSS rescore
Frequently asked(5)
What is CVE-2026-42245?
When was CVE-2026-42245 disclosed?
Is CVE-2026-42245 actively exploited?
What is the CVSS score of CVE-2026-42245?
How do I remediate CVE-2026-42245?
Dependency Blast Radius
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