CVE-2026-72916

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (46th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 6.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
6.3
EG Score
6.3MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity63% × 45%
Exploitation1% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.6%
EPSS %ILE
46th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 10, 2026

Last Modified

September 9, 2026

Advisory Details (9)

Auto-updated Aug 10, 2026
Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

v4.7.0-beta.1

Patch available: mastodon/mastodon v4.7.0-beta.1 (pre-release)

https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1
github_release Patch Available

v4.6.4

Patch available: mastodon/mastodon v4.6.4

https://github.com/mastodon/mastodon/releases/tag/v4.6.4
github_release Patch Available

v4.5.14

Patch available: mastodon/mastodon v4.5.14

https://github.com/mastodon/mastodon/releases/tag/v4.5.14
github_release Patch Available

v4.4.21

Patch available: mastodon/mastodon v4.4.21

https://github.com/mastodon/mastodon/releases/tag/v4.4.21
github_commit Patch Available

commit da47a1bd3cd0 (mastodon/mastodon)

Patch available: mastodon/mastodon v4.4.21 (contains commit da47a1bd3cd0)

https://github.com/mastodon/mastodon/commit/da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d
github_commit Patch Available

commit 930aa9fee26b (mastodon/mastodon)

Patch available: mastodon/mastodon v4.6.4 (contains commit 930aa9fee26b)

https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b
github_commit

commit 467c933459c7 (mastodon/mastodon)

Fix landed in mastodon/mastodon commit 467c933459c7 — awaiting tagged release

https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074
github_commit Patch Available

commit 18c61f286f1f (mastodon/mastodon)

Patch available: mastodon/mastodon v4.5.14 (contains commit 18c61f286f1f)

https://github.com/mastodon/mastodon/commit/18c61f286f1f5718a8f517940ba384866ffa3892
githubMentions a patch (unverified)

SSRF Protection Bypass via IPv4-compatible IPv6 Addresses · Advisory · mastodon/mastodon · GitHub

https://github.com/mastodon/mastodon/security/advisories/GHSA-vwhj-3g83-v276

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 42× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-09 20:07 UTCEPSS rescore
  3. 2026-10-08 17:13 UTCEPSS rescore
  4. 2026-10-07 23:48 UTCEPSS rescore
  5. 2026-10-06 18:17 UTCEG score recompute
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  1. 2026-09-21 21:09 UTCEPSS rescore
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  23. 2026-09-06 13:48 UTCEPSS rescore
  24. 2026-09-06 12:40 UTCEG score recompute
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  27. 2026-09-04 05:07 UTCEPSS rescore
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  34. 2026-08-31 22:03 UTCEG score recompute
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  40. 2026-08-28 21:42 UTCEPSS rescore
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  43. 2026-08-26 18:54 UTCEG score recompute
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  72. 2026-08-12 13:51 UTCEPSS rescore
  73. 2026-08-12 00:41 UTCEG score recompute
  74. 2026-08-10 22:31 UTCEG score recompute
  75. 2026-08-10 21:30 UTCEG score recompute

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Frequently asked(5)

What is CVE-2026-72916?
CVE-2026-72916 is a medium vulnerability published on August 10, 2026. 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.privateaddress? in app/lib/privateaddresscheck.rb normalized IPv4-mapped IPv6 addresses but did not recognize IPv4-compatible IPv6 addresses with…
When was CVE-2026-72916 disclosed?
CVE-2026-72916 was first published on August 10, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-72916 actively exploited?
CVE-2026-72916 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (46th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-72916?
CVE-2026-72916 has a CVSS base score of 6.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-72916?
A fix for CVE-2026-72916 is available: update to the fixed version the vendor names in its advisory.

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