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CVE-2026-42256

net-imap: Denial of service via high iteration count for `SCRAM-*` authentication

Published: May 9, 2026Updated: May 18, 2026 Sources: CVE List NVDCWE-770
NVD MITRE
6.5CVSSMEDIUM
EPSS Score
0.3%
Top 78.7%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-770CWE-1322

Affected Products

net\ruby-lang
Library
OSS Libraries / generic-library
net-imapruby
Library
OSS Libraries / rubygems
ruby-langoss-projectOSS Librariesaka ruby, rexml
rubyoss-projectJPOSS Libraries

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available
Workaround Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612
github.com
https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4
github.com
https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758
github.com
and 4 more references View all →

Timeline

Published
May 9, 2026
Last Updated
May 18, 2026

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