CVE-2026-46348Network attack vector

Unauthenticated SSRF via IPv6 unspecified address

Published Jun 24, 2026 · Updated Jun 24, 2026

SSRF in Mastodon before 4.5.10, 4.4.17, and 4.3.23 allows remote attackers to reach services bound to loopback interfaces. The outbound-request IP filter omits the IPv6 unspecified address range, so a URL resolving to :: bypasses private-address blocking. No authentication is required; exposure is limited to resources reachable from the Mastodon host through its loopback interface.

CVSS severity8.7
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Mastodon before 4.5.10, 4.4.17, and 4.3.23 allows remote attackers to reach services bound to loopback interfaces. The outbound-request IP filter omits the IPv6 unspecified address range, so a URL resolving to :: bypasses private-address blocking. No authentication is required; exposure is limited to resources reachable from the Mastodon host through its loopback interface.

The record

CVE
CVE-2026-46348
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
Mastodon
Product
Mastodon
Classifications
CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.5.0-beta.1, < 4.5.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mastodon · Mastodonversion=>= 4.5.0-beta.1, < 4.5.10

Published CVSS scores

8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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