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VulnerabilityCVE-2026-72916Published 2026-08-10

CVE-2026-72916 — mastodon

medium (derived)

As of 2026-08-10, CVE-2026-72916 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in mastodon, CVSS v4.0 6.3, EPSS 0.3% (28.7th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-72916 as of 2026-08-10; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v4.0
6.3/10Medium (derived)
EPSS
0.3%Higher than 28.7% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
0None linked yet
Priority
4.3/10Threadlinqs triage score
Published
CVSS v4.0 6.3 (Medium, derived from score) · EPSS 0.3% (higher than 28.7% of all scored CVEs) · Priority 4.3/10 · Published 2026-08-10

Last updated:

What is CVE-2026-72916?

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.

The record classifies CVE-2026-72916 under weakness classes CWE-918, CWE-1286. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 56 days ago.

Severity and exploitation probability

CVSS v4.0 base score
6.3 — Medium (derived from score)
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
EPSS (FIRST)
0.3% probability of exploitation in the next 30 days, higher than 28.7% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
4.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-08-10

Is CVE-2026-72916 being exploited?

It currently carries a trending score of 37 in the Threadlinqs vulnerability feed.

Affected products and versions

  • mastodon: mastodon

How to fix CVE-2026-72916

No vendor patch reference has been recorded for CVE-2026-72916 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-72916

No threat campaign in the Threadlinqs corpus currently references CVE-2026-72916, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch

Other references

Showing 6 of 9 recorded references.