CVE-2026-42256

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 77% 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
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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 computed
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

May 9, 2026

Last Modified

July 24, 2026

Advisory Details (7)

Auto-updated May 18, 2026
Patch available. Sources: github.
github Patch Available

Denial of service via high iteration count for `SCRAM-*` authentication · Advisory · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7
generic

Release v0.6.4 · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/releases/tag/v0.6.4
generic

Release v0.5.14 · ruby/net-imap · GitHub

https://github.com/ruby/net-imap/releases/tag/v0.5.14
generic

Release v0.4.24 · ruby/net-imap · GitHub

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

🔀 Merge pull request #654 from ruby/scram-maximum_iterations · ruby/net-imap@99f59ea · GitHub

https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758
generic

🔀 Merge pull request #656 from ruby/backport/v0.5/scram-maximum_itera… · ruby/net-imap@808001b · GitHub

https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4
generic

🔀 Merge pull request #655 from ruby/backport/v0.4/scram-maximum_itera… · ruby/net-imap@158d0b5 · GitHub

https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612

Vendor Advisories for CVE-2026-42256(5)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubunturuby3.2-doc (3.2.3-1ubuntu0.24.04.8) @ noble2026-08-23ubuntu
redhatruby3-4-main-3.4.10-31.hum12026-07-13redhat
redhatruby4-0-main-4.0.0-33.4.hum12026-06-30redhat
redhatruby3-4-main-3.4.8-31.2.hum12026-06-30redhat
redhatruby3-3-main-3.3.10-23.2.hum12026-06-30redhat

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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ruby2.72.7.4-1 ... 2.7.5-1 (8 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ruby3.13.1.2-7 ... 3.1.2-8.5 (8 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby3.33.3.8-2, 3.3.8-2.1, 3.3.8-2.2——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby3.33.3.8-2, 3.3.8-2.1, 3.3.8-2.2——
RubyGems(1)
PackageVulnerable rangeFixed inDependents
net-imap0.4.0 ... 0.4.9.1 (25 versions)0.4.24—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 54× 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 146 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-42256?
CVE-2026-42256 is a medium vulnerability published on May 9, 2026. Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational…
When was CVE-2026-42256 disclosed?
CVE-2026-42256 was first published in the National Vulnerability Database on May 9, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42256 actively exploited?
CVE-2026-42256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.1% of all scored CVEs.
What is the CVSS score of CVE-2026-42256?
CVE-2026-42256 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-42256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42256, 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.

Dependency Blast Radius

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