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: 0.4%, top 71% of all CVEs by exploit prediction. 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%CVSS: 6.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
6.3(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: Track

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%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

August 10, 2026

Last Modified

August 13, 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
github Patch Available

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 11× in last 7d / 33× 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.

  1. 2026-08-26 14:47 UTCEPSS rescore
  2. 2026-08-25 16:37 UTCEG score recompute
  3. 2026-08-25 13:49 UTCEPSS rescore
  4. 2026-08-24 14:27 UTCEG score recompute
  5. 2026-08-23 12:16 UTCEG score recompute
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-22 10:06 UTCEG score recompute
  8. 2026-08-21 23:49 UTCEPSS rescore
  9. 2026-08-21 07:53 UTCEG score recompute
  10. 2026-08-20 22:56 UTCEPSS rescore
  11. 2026-08-20 05:43 UTCEG score recompute
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-19 03:32 UTCEG score recompute
  14. 2026-08-18 13:49 UTCEPSS rescore
  15. 2026-08-18 13:49 UTCEPSS rescore
  16. 2026-08-18 01:22 UTCEG score recompute
  17. 2026-08-17 13:47 UTCEPSS rescore
  18. 2026-08-16 23:07 UTCEG score recompute
  19. 2026-08-16 14:56 UTCEPSS rescore
  20. 2026-08-16 14:56 UTCEPSS rescore
  21. 2026-08-16 02:15 UTCEPSS rescore
  22. 2026-08-15 20:57 UTCEG score recompute
  23. 2026-08-15 01:31 UTCEPSS rescore
  24. 2026-08-14 18:46 UTCEG score recompute
  25. 2026-08-13 22:00 UTCEPSS rescore
Show 8 more
  1. 2026-08-13 16:36 UTCEG score recompute
  2. 2026-08-13 15:34 UTCEG score recompute
  3. 2026-08-13 02:51 UTCEG score recompute
  4. 2026-08-12 13:51 UTCEPSS rescore
  5. 2026-08-12 00:41 UTCEG score recompute
  6. 2026-08-10 22:31 UTCEG score recompute
  7. 2026-08-10 21:30 UTCEG score recompute
  8. 2026-08-10 21:29 UTCMITRE cvelistV5first tracked

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 in the National Vulnerability Database on August 10, 2026, with the most recent update on August 13, 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% probability of exploitation in the next 30 days, which ranks it in the top 71.3% of all scored CVEs.
What is the CVSS score of CVE-2026-72916?
CVE-2026-72916 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-72916?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-72916, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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