GHSA-w254-4hp5-7cvv CVE-2026-34388 GO-2026-4915
Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.27%
- Chance of exploitation in the next 30 days. Higher than 19.75% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-703 Improper Check or Handling of Exceptional Conditions
- Fix
4.81.0- Upgrade github.com/fleetdm/fleet/v4 to this version or later
Description
Summary
A Denial of Service vulnerability in Fleet's gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers.
Impact
An attacker with access to a valid Launcher node key can send a specially crafted gRPC request to the Fleet server that triggers an unrecoverable server crash. The gRPC server lacks appropriate error recovery handling, meaning the entire Fleet process terminates rather than gracefully rejecting the malformed input.
Because the crash is instant and repeatable, an attacker could script repeated requests to prevent the server from recovering, resulting in a persistent denial of service until a patched version is deployed.
Workarounds
There is no workaround for this issue other than upgrading to a patched version.
For more information
If there are any questions or comments about this advisory:
Send an email to security@fleetdm.com
Join #fleet in osquery Slack
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:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Unreported
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-703: Improper Check or Handling of Exceptional Conditions
The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.
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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