---
cve: "CVE-2026-71847"
severity: "HIGH"
cvss: 8.7
epss: "25%"
vendor: "Ruby"
kev: false
exploited: false
published: "2026-08-07 19:18:53"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-09T23:04:17+02:00"
---

# CVE-2026-71847

> 8.7 HIGH · 🧪 PoC

## Beschreibung

Ruby JSON is a JSON implementation for Ruby. From 2.20.0 until 2.21.2, Ruby's JSON native C extension clears the consumed JSON::ResumableParser input buffer but leaves state.start, state.cursor, and state.end pointing into released storage. When partial_value reconstructs an incomplete object containing duplicate keys, the duplicate-key warning path calls cursor_position, which dereferences those stale pointers. This results in a heap-use-after-free and can terminate the Ruby process. An attacker who can supply JSON stream data to an application using JSON::ResumableParser may cause process termination when the application calls partial_value on incomplete attacker-controlled input containing duplicate object keys. This issue has been fixed in version 2.21.2.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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 |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 5a32e4367ca5976f62af12887a09685b7109b054 (Commit)

## Referenzen

- <https://github.com/ruby/json/security/advisories/GHSA-9hj4-r449-hfvc>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-71847) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_