---
cve: "CVE-2026-72916"
severity: "MEDIUM"
cvss: 6.3
epss: "36%"
vendor: "mastodon"
kev: false
exploited: false
published: "2026-08-10 22:17:10"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-14T21:46:23+02:00"
---

# CVE-2026-72916

> 6.3 MEDIUM · 🧪 PoC

## Beschreibung

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.21, 4.5.14, 4.6.4, and 4.7.0-beta.1, PrivateAddressCheck.private_address? in app/lib/private_address_check.rb normalized IPv4-mapped IPv6 addresses but did not recognize IPv4-compatible IPv6 addresses with IPAddr#ipv4_compat?. An attacker could supply an address in the omitted range to bypass the ALLOWED_PRIVATE_ADDRESSES protection and make Mastodon send HTTP requests to loopback interfaces, potentially accessing private resources and services. Exploitation requires a system that supports the obsolete IPv4-compatible IPv6 mechanism. This issue is fixed in versions 4.4.21, 4.5.14, 4.6.4, and 4.7.0-beta.1.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d (Commit)
- 18c61f286f1f5718a8f517940ba384866ffa3892 (Commit)

## Referenzen

- <https://github.com/mastodon/mastodon/security/advisories/GHSA-vwhj-3g83-v276>
- <https://github.com/mastodon/mastodon/commit/18c61f286f1f5718a8f517940ba384866ffa3892>
- <https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074>
- <https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b>
- <https://github.com/mastodon/mastodon/commit/da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d>
- <https://github.com/mastodon/mastodon/releases/tag/v4.4.21>
- <https://github.com/mastodon/mastodon/releases/tag/v4.5.14>
- <https://github.com/mastodon/mastodon/releases/tag/v4.6.4>
- <https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-72916) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_