CVE-2026-42256 PUBLISHED

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

Assigner: GitHub_M
Reserved: 26.04.2026 Published: 09.05.2026 Updated: 09.05.2026

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.

Metrics

CVSS 4.0

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
CVSS Score: 6

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	High	Availability	None
Privileges Required	None
User Interaction	Passive

CVSS 4.0

Product Status

Vendor	ruby
Product	net-imap
Versions	Version >= 0.4.0, < 0.4.24 is affected Version >= 0.5.0, < 0.5.14 is affected Version >= 0.6.0, < 0.6.4 is affected

References

Problem Types

CWE-1322: Use of Blocking Code in Single-threaded, Non-blocking Context CWE
CWE-770: Allocation of Resources Without Limits or Throttling CWE