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🛡️ CVE-2026-26062 — fleet

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-20 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Fleet server may terminate unexpectedly when handling certain gRPC requests

Summary

Fleet contained a denial-of-service (DoS) issue in the gRPC Launcher PublishLogs endpoint. In affected versions, certain unexpected input values were not handled gracefully, which could cause the Fleet server process to terminate while processing an authenticated request from an enrolled Launcher host.

Impact

An authenticated attacker with access to any enrolled Launcher node key could cause an immediate and complete denial of service by sending a single gRPC request to the PublishLogs endpoint.

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:

  • Restrict network access to the Fleet gRPC endpoint where feasible (for example, limiting inbound access to known host IP ranges).
  • Deploy Fleet behind infrastructure that terminates or filters gRPC traffic if Launcher log ingestion is not required.
  • Monitor for repeated Fleet process crashes or unexpected restarts indicating potential exploitation.

For More Information

If you have any questions or concerns about this advisory, please contact us at:

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

Credits

We thank @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 low-level 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:L/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: Low — an ordinary user account is enough.
  • 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-2026-26062 is classified as CWE-20: Improper Input Validation. The application accepts input without checking that it has the expected form, so malformed values reach code that assumes they are well formed.

Affected software

CVE-2026-26062 is recorded against 2 packages.

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

Timeline and source

Published on 14 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
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-20: Improper Input Validation) in other software:

Details

Severity MEDIUM
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE CWE-20
Public Exploit ✅ No
Source NVD
Published 2026-05-14
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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