Is CVE-2026-47389 in the CISA KEV catalog?

No. CVE-2026-47389 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-47389?

CVE-2026-47389 has a CVSS v3 base score of 8.6 (HIGH).

What is the EPSS score for CVE-2026-47389?

CVE-2026-47389 has an EPSS score of 0.23% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-47389?

No published fix for CVE-2026-47389 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-47389

HIGH

8.6

CVSS v3

NVD

Description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.private_address? returns false for IPv4-mapped IPv6 addresses (::ffff:a.b.c.d) corresponding to some private IPv4 addresses, depending on Ruby version, this can include loopback, RFC1918 private networks, and link-local space. An attacker who controls DNS for any domain can publish an AAAA record with such a mapped address; any outbound HTTP fetch Mastodon performs against that hostname then opens a real TCP connection to the underlying IPv4 address, including 127.0.0.1 and cloud-metadata endpoints such as 169.254.169.254. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

CWE-184 CWE-200Information Exposure CWE-918Server-Side Request Forgery (SSRF)

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Exploit Intelligence

0.23%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Other references1

github.com

Embed a live status badge for CVE-2026-47389

Markdown

[![CVE-2026-47389](https://tridentstack.com/cve/badge/CVE-2026-47389.svg)](https://tridentstack.com/cve/CVE-2026-47389)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-47389"><img src="https://tridentstack.com/cve/badge/CVE-2026-47389.svg" alt="CVE-2026-47389"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.