CVE-2026-42256net-imap: Denial of service via high iteration count for `SCRAM-*` authentication
- 6.0MediumCVSS base score
- 0.30%Exploitation in 30 daysEPSS · top 77% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By GitHub_M
- 13 days later
· 13 days later
Published
- 2 days later
· 2 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | Medium6.0 | 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 |
| NVDNVD · Analyzed | 4.0 | Medium6.0 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.30% · top 77% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.0.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- RubyGemsnet-imapGHSA-87pf-fpwv-p7m7 (opens in a new tab)
References
References7
- https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612 (opens in a new tab)x_refsource_MISC
- https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4 (opens in a new tab)x_refsource_MISC
- https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758 (opens in a new tab)x_refsource_MISC
- https://github.com/ruby/net-imap/releases/tag/v0.4.24 (opens in a new tab)x_refsource_MISC
- https://github.com/ruby/net-imap/releases/tag/v0.5.14 (opens in a new tab)x_refsource_MISC
- https://github.com/ruby/net-imap/releases/tag/v0.6.4 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-28925 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-87pf-fpwv-p7m7 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-42256)Record last updated .