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🛡️ CVE-2026-26061 — fleet

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-770 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Fleet's unbounded request body read allows remote Denial of Service

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 [security@fleetdm.com](mailto:[email protected])

Credits

Fleet thanks @fuzzztf for responsibly reporting this issue.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-26061 is classified as CWE-770: Allocation of Resources Without Limits. Resources are allocated on request with no cap, so a client can exhaust them.

Affected software

CVE-2026-26061 is recorded against 2 packages.

  • fleet (fixed in 4.81.0)
  • github.com/fleetdm/fleet/v4

Timeline and source

Published on 27 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com

Other advisories for this package

fleet has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-770: Allocation of Resources Without Limits) in other software:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-770
Public Exploit ✅ No
Source NVD
Published 2026-03-27
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
fleet — 4.81.0
github.com/fleetdm/fleet/v4 — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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