How severe is CVE-2026-46348?

CVE-2026-46348 has a CVSS 4.0 base score of 8.7, rated high severity.

Is CVE-2026-46348 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-46348?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-46348 have an EU (EUVD) identifier?

Yes. CVE-2026-46348 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39053.

When was CVE-2026-46348 published?

CVE-2026-46348 was published on 2026-06-24 and last updated on 2026-06-25.

CVE-2026-46348

CVE-2026-46348 is a high-severity vulnerability with a CVSS 4.0 base score of 8.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.

Key facts

Severity: High (CVSS 4.0 base score 8.7)
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39053
Weakness: CWE-918
Published: 2026-06-24
Last modified: 2026-06-25

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, the list of disallowed IP address ranges was lacking an IP address range that can be used to reach local IP addresses. An attacker can use an IP address in the affected range to make Mastodon perform HTTP requests against loopback interfaces, potentially allowing access to otherwise private resources and services. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

Frequently asked questions

What is CVE-2026-46348?: Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, the list of disallowed IP address ranges was lacking an IP address range that can be used to reach local IP addresses. An attacker can use an IP address in the affected range to make Mastodon perform HTTP requests against loopback interfaces, potentially allowing access to otherwise private resources and services. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.
How severe is CVE-2026-46348?: CVE-2026-46348 has a CVSS 4.0 base score of 8.7, rated high severity.
Is CVE-2026-46348 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-46348?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-46348 have an EU (EUVD) identifier?: Yes. CVE-2026-46348 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39053.
When was CVE-2026-46348 published?: CVE-2026-46348 was published on 2026-06-24 and last updated on 2026-06-25.

References

https://github.com/mastodon/mastodon/security/advisories/GHSA-crr4-7rm4-8gpw

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