CVE-2026-42256

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.

Scoring

Severity

MEDIUM

CVSS base score

6

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

EPSS probability

0.30%

CWE

CWE-1322, CWE-770

Published

2026-05-09

Last modified

2026-05-11

Affected products

• ruby net-imap
• ruby net-imap
• ruby net-imap

Weakness type

• CWE-1322
• CWE-770

Related vulnerabilities

• CVE-2026-19484 — @fastify/busboy vulnerable to Denial of Service via oversized multipart boundary
• CVE-2026-71439 — Mermaid radar diagrams are vulnerable to DoS

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