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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
ruby net-imap affected
Version Status Constraints
>= 0.4.0, < 0.4.24 affected —
>= 0.5.0, < 0.5.14 affected —
>= 0.6.0, < 0.6.4 affected —

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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-87pf-fpwv-p7m7 net-imap vulnerable to denial of service via high iteration count for `SCRAM-*` authentication
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612 cve-icon cve-icon
https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4 cve-icon cve-icon
https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758 cve-icon cve-icon
https://github.com/ruby/net-imap/releases/tag/v0.4.24 cve-icon cve-icon
https://github.com/ruby/net-imap/releases/tag/v0.5.14 cve-icon cve-icon
https://github.com/ruby/net-imap/releases/tag/v0.6.4 cve-icon cve-icon
https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7 cve-icon cve-icon
History

Sat, 09 May 2026 20:00:00 +0000

Type Values Removed Values Added
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.
Title net-imap: Denial of service via high iteration count for `SCRAM-*` authentication
Weaknesses CWE-1322
CWE-770
References
Metrics cvssV4_0

{'score': 6, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-09T19:38:33.106Z

Reserved: 2026-04-26T11:53:27.704Z

Link: CVE-2026-42256

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-09T20:16:28.313

Modified: 2026-05-09T20:16:28.313

Link: CVE-2026-42256

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-09T21:30:42Z

Weaknesses