Mastodon is a free, open-source social network server based on ActivityPub. FASP registration requires manual approval by an administrator. In versions 4.4.0 through 4.4.13 and 4.5.0 through 4.5.6, actions performed by a FASP to subscribe to account/content lifecycle events or to backfill content did not check properly whether the FASP was actually approved. This only affects Mastodon servers that have opted in to testing the experimental FASP feature by setting the environment variable EXPERIMENTAL_FEATURES to a value including fasp. An attacker can make subscriptions and request content backfill without approval by an administrator. Done once, this leads to minor information leak of URIs that are publicly available anyway. But done several times this is a serious vector for DOS, putting pressure on the sidekiq worker responsible for the fasp queue. The fix is included in the 4.4.14 and 4.5.7 releases. Admins that are actively testing the experimental "fasp" feature should update their systems. Servers not using the experimental feature flag fasp are not affected.
CVE-2026-27468
This high-severity CVE scores 8.2 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.2
- EG Score
- 8.2(low)
- EG Risk
- 41(Track)EG Risk 41/100SSVC: 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 computedSeverity82% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 16%
- KEV
- Not listed
Published
February 24, 2026
Last Modified
June 17, 2026
References (2)
- security-advisories@githubhttps://github.com/mastodon/mastodon/commit/6ba6285a73c3a8b281123814d45f534e3bcebb96
- security-advisories@githubhttps://github.com/mastodon/mastodon/security/advisories/GHSA-qgmm-vr4c-ggjg
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× 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.
- 2026-07-30 16:27 UTCEPSS rescore
- 2026-07-30 01:30 UTCEPSS rescore
- 2026-07-28 15:36 UTCEPSS rescore
- 2026-07-27 14:08 UTCEG score recompute
Frequently asked(5)
What is CVE-2026-27468?
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Is CVE-2026-27468 actively exploited?
What is the CVSS score of CVE-2026-27468?
How do I remediate CVE-2026-27468?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-27468
Is Your Infrastructure Affected by CVE-2026-27468?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.