AUGUST 15, 2026
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Case File

CVE-2026-72916

MEDIUM · CVSS 6.3 EPSS 0.36% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-08-10 · Last synced 2026-08-15

CyberRota Analysis

AI-Generated

Mastodon versions prior to 4.4.21, 4.5.14, 4.6.4, and 4.7.0-beta.1 are vulnerable to an issue where the PrivateAddressCheck mechanism fails to recognize IPv4-compatible IPv6 addresses, allowing attackers to bypass protections and send HTTP requests to loopback interfaces. This could lead to unauthorized access to private resources and services. Organizations using affected versions should prioritize upgrading to the patched releases to mitigate potential exploitation risks.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-72916
Severity
MEDIUM
CVSS
6.3
EPSS
0.36%

Original NVD Description

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.