CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
4Description
### Summary Fleet contained multiple unauthenticated HTTP endpoints that read request bodies without enforcing a size limit. An unauthenticated attacker could exploit this behavior by sending large or repeated HTTP payloads, causing excessive memory allocation and resulting in a denial-of-service (DoS) condition. ### Impact An unauthenticated attacker could cause the Fleet server process to exhaust available memory and restart by sending oversized or repeated HTTP requests to affected endpoints. This vulnerability impacts **availability only**. There is: - No exposure of sensitive data - No authentication bypass - No privilege escalation - No integrity impact ### Workarounds If upgrading immediately is not possible, the following mitigations can reduce exposure: - Apply request body size limits at a reverse proxy or load balancer (e.g., NGINX, Envoy). - Restrict network access to endpoints to known IP ranges where feasible. - Monitor memory usage and restart frequency for abnormal patterns. ### For More Information If there are any questions or concerns about this advisory, please contact us at: Email Fleet at [[email protected]](mailto:[email protected]) ### Credits Fleet thanks @fuzzztf for responsibly reporting this issue.
Analysis
Fleet server memory exhaustion via unbounded request bodies allows unauthenticated denial-of-service against multiple HTTP endpoints. The vulnerability affects Fleet v4 (github.com/fleetdm/fleet/v4) and was responsibly disclosed by @fuzzztf. …
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Remediation
Within 24 hours: Implement network-level request size limits and rate limiting on Fleet HTTP endpoints; document current Fleet v4 version in use. Within 7 days: Deploy WAF rules to enforce maximum request body sizes (recommend 1MB limit) on all unauthenticated Fleet endpoints; segment Fleet server network access where feasible. …
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-16744
GHSA-99hj-44vg-hfcp