---
cve: "CVE-2026-105221"
severity: "CRITICAL"
cvss: 9.1
epss: "0.2%"
vendor: "defunkt"
kev: false
exploited: false
published: "2026-10-04 23:16:59"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-10-24T02:32:23+02:00"
---

# CVE-2026-105221

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

The gist RubyGem before 6.1.0 contains an improper certificate validation vulnerability that allows on-path attackers to intercept HTTPS traffic because http_connection in lib/gist.rb sets VERIFY_NONE. Attackers can present any certificate to read or modify GitHub API traffic, stealing OAuth tokens and login credentials to read and modify the victim's gists.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-10-05 20:28:43
- CNA-CVSS: **9.1** (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Schwachstellen-Klasse

- **CWE-295** — Improper Certificate Validation
  The product does not validate, or incorrectly validates, a certificate.

## Angriffsmuster (CAPEC)

- [CAPEC-459 — Creating a Rogue Certification Authority Certificate](https://capec.mitre.org/data/definitions/459.html) _(Severity: Very High)_
- [CAPEC-475 — Signature Spoofing by Improper Validation](https://capec.mitre.org/data/definitions/475.html) _(Severity: High)_

## Patch verfügbar (OSV)

- 9c684d1f683460b9501e3efcb95edcb32487ddfe (Commit)
- 07ccc1a6d46e9d36f0e85d0b1c5d795890ae6bcf (Commit)

## Referenzen

- <https://github.com/defunkt/gist/issues/373>
- <https://github.com/defunkt/gist>
- <https://github.com/defunkt/gist/blob/v6.0.0/lib/gist.rb#L466-L468>
- <https://github.com/defunkt/gist/commit/07ccc1a6d46e9d36f0e85d0b1c5d795890ae6bcf>
- <https://www.vulncheck.com/advisories/gist-rubygem-before-6.1.0-disabled-tls-certificate-verification>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-105221/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_