Bug 2468500 (CVE-2026-42256)

Summary:	CVE-2026-42256 ruby/net-imap: ruby: Net::IMAP: Denial of Service via large iteration count in SCRAM authentication
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akostadi, amasferr, dmayorov, eshamard, jkoehler, jlledo, jvasik, kaycoth, lphiri, pantinor, rblanco, rhel-process-autobot, sdawley, tsedmik, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in Net::IMAP, a Ruby library for Internet Message Access Protocol (IMAP) client functionality. A hostile server can exploit this vulnerability during SCRAM-SHA1 or SCRAM-SHA256 (Salted Challenge Response Authentication Mechanism - Secure Hash Algorithm 1 or 256) authentication by sending an excessively large iteration count value. This can lead to a computational denial-of-service attack, causing the client process to become unresponsive.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-09 20:01:31 UTC

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.

Comment 3 errata-xmlrpc 2026-08-05 09:40:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:50728 https://access.redhat.com/errata/RHSA-2026:50728

Comment 4 errata-xmlrpc 2026-08-05 11:21:44 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:50773 https://access.redhat.com/errata/RHSA-2026:50773

Comment 5 errata-xmlrpc 2026-08-05 12:04:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:50778 https://access.redhat.com/errata/RHSA-2026:50778

Comment 6 errata-xmlrpc 2026-08-05 16:37:10 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:50828 https://access.redhat.com/errata/RHSA-2026:50828

Comment 7 errata-xmlrpc 2026-08-05 16:40:18 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:50827 https://access.redhat.com/errata/RHSA-2026:50827