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🛡️ CVE-2026-34389 — fleet

🟡 CVSS 6.5 — Medium ✅ No Known Exploit CWE-287 NVD
6.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Fleet's user account creation via invite does not enforce invited email address

Summary

Fleet contained an issue in the user invitation flow where the email address provided during invite acceptance was not validated against the email address associated with the invite. An attacker who obtained a valid invite token could create an account under an arbitrary email address while inheriting the role granted by the invite, including global admin.

Impact

If an attacker gains access to a valid invite token, they can create a Fleet user account with an email address of their choosing while inheriting the invite’s assigned role and team memberships.

This issue:

  • Requires possession of a valid invite token
  • Does not bypass authentication controls beyond invite-based account creation
  • Does not expose data without successful account creation

Workarounds

If upgrading immediately is not possible:

  • Treat invite links as sensitive credentials and avoid sharing them in public or semi-public channels (e.g., Slack, Teams).
  • Revoke and reissue invites if there is any concern that an invite link may have been exposed.
  • Prefer issuing invites with the minimum required privileges and elevating roles after account creation when appropriate.

For more information

If there are any questions or comments about this advisory:

Send an email to [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 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 high, availability none.

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:H/A:N

  • 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: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

CVE-2026-34389 is classified as CWE-287: Improper Authentication. The identity of the caller is not established correctly, so an attacker can act as another user.

Affected software

CVE-2026-34389 is recorded against 2 packages.

  • fleet (fixed in 4.81.1)
  • 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-287: Improper Authentication) in other software:

Details

Severity MEDIUM
CVSS Score 6.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
CWE CWE-287
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 — 4.81.1
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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