CVE-2026-42257

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 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).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
34.6%
KEV
Not listed

Published

May 9, 2026

Last Modified

May 18, 2026

Advisory Details (4)

Auto-updated Jun 21, 2026
Patch available. Sources: github_release, github.
github Patch Available

Command Injection via "raw" arguments to multiple commands · Advisory · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/security/advisories/GHSA-hm49-wcqc-g2xg
github_release Patch Available

v0.6.4

Patch available: ruby/net-imap v0.6.4

https://github.com/ruby/net-imap/releases/tag/v0.6.4
github_release Patch Available

v0.5.14

Patch available: ruby/net-imap v0.5.14

https://github.com/ruby/net-imap/releases/tag/v0.5.14
github_release Patch Available

v0.4.24

Patch available: ruby/net-imap v0.4.24

https://github.com/ruby/net-imap/releases/tag/v0.4.24

Vendor Advisories for CVE-2026-42257(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubunturuby2.3-tcltk (2.3.1-2~ubuntu16.04.16+esm14) @ xenial2026-06-28ubuntu

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)
PackageVulnerable rangeFixed inDependents
net-imap0.1.0 ... 0.4.9.1 (45 versions)0.4.24—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 64× 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.

Showing the most recent 100 of 178 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
  3. 2026-07-08 15:15 UTCEPSS rescore
  4. 2026-07-07 13:46 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 16:27 UTCEPSS rescore
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-06 02:23 UTCEPSS rescore
  9. 2026-07-05 02:30 UTCEPSS rescore
  10. 2026-07-04 06:31 UTCEPSS rescore
  11. 2026-07-01 15:06 UTCEPSS rescore
  12. 2026-06-30 23:22 UTCEPSS rescore
  13. 2026-06-29 14:06 UTCEPSS rescore
  14. 2026-06-28 14:07 UTCEPSS rescore
  15. 2026-06-28 08:54 UTCEG score recompute
  16. 2026-06-28 08:54 UTCVendor advisory
  17. 2026-06-28 04:56 UTCEPSS rescore
  18. 2026-06-28 03:43 UTCEG score recompute
  19. 2026-06-28 03:43 UTCVendor advisory
  20. 2026-06-27 14:25 UTCEG score recompute
  21. 2026-06-27 14:25 UTCVendor advisory
  22. 2026-06-27 10:31 UTCEG score recompute
  23. 2026-06-27 10:31 UTCVendor advisory
  24. 2026-06-27 03:08 UTCEPSS rescore
  25. 2026-06-26 21:12 UTCEG score recompute
Show 75 more
  1. 2026-06-26 05:46 UTCEG score recompute
  2. 2026-06-26 05:46 UTCVendor advisory
  3. 2026-06-25 13:49 UTCEPSS rescore
  4. 2026-06-25 13:49 UTCEPSS rescore
  5. 2026-06-24 14:05 UTCEPSS rescore
  6. 2026-06-23 21:33 UTCEPSS rescore
  7. 2026-06-22 14:25 UTCEPSS rescore
  8. 2026-06-22 14:25 UTCEPSS rescore
  9. 2026-06-21 14:56 UTCEPSS rescore
  10. 2026-06-21 14:56 UTCEPSS rescore
  11. 2026-06-21 01:59 UTCEPSS rescore
  12. 2026-06-19 19:25 UTCEPSS rescore
  13. 2026-06-18 17:52 UTCEPSS rescore
  14. 2026-06-18 17:52 UTCEPSS rescore
  15. 2026-06-17 17:53 UTCEPSS rescore
  16. 2026-06-17 05:42 UTCEG score recompute
  17. 2026-06-17 01:15 UTCEG score recompute
  18. 2026-06-17 01:15 UTCVendor advisory
  19. 2026-06-16 17:52 UTCEPSS rescore
  20. 2026-06-16 07:50 UTCEG score recompute
  21. 2026-06-16 07:50 UTCVendor advisory
  22. 2026-06-15 17:49 UTCEPSS rescore
  23. 2026-06-15 06:21 UTCEG score recompute
  24. 2026-06-15 02:25 UTCEG score recompute
  25. 2026-06-14 22:32 UTCEG score recompute
  26. 2026-06-14 18:33 UTCEG score recompute
  27. 2026-06-14 14:40 UTCEG score recompute
  28. 2026-06-14 10:43 UTCEG score recompute
  29. 2026-06-14 06:44 UTCEG score recompute
  30. 2026-06-14 02:21 UTCEG score recompute
  31. 2026-06-13 23:00 UTCEPSS rescore
  32. 2026-06-13 09:12 UTCEG score recompute
  33. 2026-06-12 23:12 UTCEPSS rescore
  34. 2026-06-12 23:12 UTCEPSS rescore
  35. 2026-06-12 22:45 UTCEG score recompute
  36. 2026-06-12 18:32 UTCEG score recompute
  37. 2026-06-12 12:38 UTCEG score recompute
  38. 2026-06-12 08:43 UTCEG score recompute
  39. 2026-06-12 04:49 UTCEG score recompute
  40. 2026-06-12 00:55 UTCEG score recompute
  41. 2026-06-11 21:02 UTCEG score recompute
  42. 2026-06-11 17:08 UTCEG score recompute
  43. 2026-06-11 14:00 UTCEPSS rescore
  44. 2026-06-11 12:12 UTCEG score recompute
  45. 2026-06-11 08:12 UTCEG score recompute
  46. 2026-06-11 04:17 UTCEG score recompute
  47. 2026-06-11 00:19 UTCEG score recompute
  48. 2026-06-10 22:18 UTCEPSS rescore
  49. 2026-06-10 19:39 UTCEG score recompute
  50. 2026-06-10 15:45 UTCEG score recompute
  51. 2026-06-10 13:22 UTCEPSS rescore
  52. 2026-06-10 13:22 UTCEPSS rescore
  53. 2026-06-10 11:52 UTCEG score recompute
  54. 2026-06-10 07:58 UTCEG score recompute
  55. 2026-06-10 03:48 UTCEG score recompute
  56. 2026-06-09 23:55 UTCEG score recompute
  57. 2026-06-09 20:02 UTCEG score recompute
  58. 2026-06-09 16:06 UTCEG score recompute
  59. 2026-06-09 12:13 UTCEG score recompute
  60. 2026-06-09 08:18 UTCEG score recompute
  61. 2026-06-09 04:21 UTCEG score recompute
  62. 2026-06-09 00:27 UTCEG score recompute
  63. 2026-06-08 20:33 UTCEG score recompute
  64. 2026-06-08 14:56 UTCEG score recompute
  65. 2026-06-08 14:17 UTCEPSS rescore
  66. 2026-06-08 14:17 UTCEPSS rescore
  67. 2026-06-08 11:03 UTCEG score recompute
  68. 2026-06-08 07:08 UTCEG score recompute
  69. 2026-06-08 03:14 UTCEG score recompute
  70. 2026-06-07 23:21 UTCEG score recompute
  71. 2026-06-07 19:27 UTCEG score recompute
  72. 2026-06-07 15:34 UTCEG score recompute
  73. 2026-06-07 15:25 UTCEPSS rescore
  74. 2026-06-07 15:25 UTCEPSS rescore
  75. 2026-06-07 11:41 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-42257?
CVE-2026-42257 is a critical vulnerability published on May 9, 2026. 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, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled…
When was CVE-2026-42257 disclosed?
CVE-2026-42257 was first published in the National Vulnerability Database on May 9, 2026, with the most recent update on May 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42257 actively exploited?
CVE-2026-42257 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42257?
CVE-2026-42257 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-42257?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42257, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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