# CVE-2026-42256

## Summary

- **CVE ID:** CVE-2026-42256
- **Severity:** MEDIUM
- **CVSS Score:** 6 (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-1322, CWE-770
- **Published:** May 9, 2026
- **Last Modified:** May 11, 2026

## Description

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.

## Affected Products

- ruby — net-imap (>= 0.4.0, < 0.4.24)
- ruby — net-imap (>= 0.5.0, < 0.5.14)
- ruby — net-imap (>= 0.6.0, < 0.6.4)

## References

- [CNA](https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7)
- [CNA](https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612)
- [CNA](https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4)
- [CNA](https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758)
- [CNA](https://github.com/ruby/net-imap/releases/tag/v0.4.24)
- [CNA](https://github.com/ruby/net-imap/releases/tag/v0.5.14)
- [CNA](https://github.com/ruby/net-imap/releases/tag/v0.6.4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.30%
- **EPSS Percentile:** 22.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._