Medium 6.0Published May 9, 2026

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

Updated under an hour ago (Oct 27, 2026, 8:00 AM ET)

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It affects ruby net-imap and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for ruby net-imap

Exploited in the last 30 days

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: 6.0 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-1322, CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 11, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

ruby net-imap ruby:net_imap (from the name)	from 0.4.0, < 0.4.24; from 0.5.0, < 0.5.14; from 0.6.0, < 0.6.4	CNA record
ruby-lang net::imap ruby-lang:net::imap	from 0.4.0 before 0.4.24; from 0.5.0 before 0.5.14; from 0.6.0 before 0.6.4	NVD

References

References

https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7	x-refsource-confirm, mitigation, vendor-advisory
https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612	x-refsource-misc, patch
https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4	x-refsource-misc, patch
https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758	x-refsource-misc, patch
https://github.com/ruby/net-imap/releases/tag/v0.4.24	x-refsource-misc, release-notes
https://github.com/ruby/net-imap/releases/tag/v0.5.14	x-refsource-misc, release-notes
https://github.com/ruby/net-imap/releases/tag/v0.6.4	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.