CVE-2026-42256
net-imap: Denial of service via high iteration count for `SCRAM-*` authentication
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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
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7
- https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612
- https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4
- https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758
References (7)
SSVC — Action Prioritization
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- NONE
- Availability
- HIGH
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