GHSA-4f9r-x588-pp2h CVE-2026-34389 GO-2026-4912
Fleet's user account creation via invite does not enforce invited email address
- Severity
- 0.0 / 10
- Medium · CVSS 4.0
- Exploit chance (EPSS)
- 0.19%
- Chance of exploitation in the next 30 days. Higher than 8.86% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-287 Improper Authentication
- Fix
4.81.0- Upgrade github.com/fleetdm/fleet/v4 to this version or later
Description
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
Credits
Fleet thanks @fuzzztf for responsibly reporting this issue.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/fleetdm/fleet/v4 | < 4.81.0 |
4.81.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/fleetdm/fleet/v4 Go → 4.81.0
- go
go get github.com/fleetdm/fleet/v4@v4.81.0 && go mod tidy
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Unreported
CVSS 3.1 6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Weakness
CWE-287: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How to prevent it
- Architecture and Design: Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-rxhg-vcww-2mpw Fleet: ORDER BY column injection on activity list endpoints | Low | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-q9c5-pp7m-fm2g Fleet: Unauthenticated download of in-house iOS app binaries via predictable URLs | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GO-2026-6264 Fleet: SQL injection in Okta conditional access endpoint allows host-controlled compromise of the Fleet database | High | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-88p2-jj8w-j8qg Fleet: Observer-class users can view team enroll secrets and credential-bearing configuration via target search endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-gm7f-v959-fr2g Fleet DM Vulnerable to Cross-Team Policy Data Exposure via Global Policy Read Endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-x4qr-qw6h-wvxq Fleet: Observer-level enrollment secret extraction via ORDER BY oracle on Apple MDM commands endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-vxm7-9x8v-8gm4 Fleet has observer-level enrollment secret extraction via ORDER BY oracle on labels host-listing endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-mxmp-wr3w-rvqx Fleet: IP spoofing allows bypassing API rate limiting | High | Also affects github.com/fleetdm/fleet/v4 |
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