---
cve: "CVE-2026-42256"
severity: "MEDIUM"
cvss: 6.0
epss: "30%"
vendor: "Ruby"
kev: false
exploited: false
published: "2026-05-09 20:16:28"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T08:29:38+02:00"
---

# CVE-2026-42256

> 6.0 MEDIUM · 🧪 PoC

## Beschreibung

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-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- 24a4e770b43230286a05aa2a9746cdbb3eb8485e (Commit)
- 4063bc1d1d3e21046544ed7a2c131e5f886bab01 (Commit)

## Referenzen

- <https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7>
- <https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612>
- <https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4>
- <https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758>
- <https://github.com/ruby/net-imap/releases/tag/v0.4.24>
- <https://github.com/ruby/net-imap/releases/tag/v0.5.14>
- <https://github.com/ruby/net-imap/releases/tag/v0.6.4>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-42256) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_