CVE-2026-42256 MEDIUM

CVE-2026-42256: net-imap: Denial of service via high iteration count for `SCRAM-*` authentication

Vendor Ruby
Product net-imap
Weakness CWE-1322
Published May 9, 2026
Last update May 11, 2026

CVSS base score

6.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction
Confidentiality
Integrity

CVSS 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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 9, 2026 CVE published
May 11, 2026 Record updated