How severe is CVE-2026-23517?

No CVSS score has been assigned to CVE-2026-23517 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-23517?

CVE-2026-23517 affects the following packages: github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet/v4 (Go). Ecosystems affected: Go.

How do I fix CVE-2026-23517?

Update github.com/fleetdm/fleet to 4.78.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23517 is resolved across your whole dependency graph.

How do I detect CVE-2026-23517 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fleetdm/fleet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-23517 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-23517 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-23517 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-23517?

CVE-2026-23517 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 22th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-23517?

CVE-2026-23517 is classified as CWE-862 (CWE-862). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-23517 published, and has it been updated?

CVE-2026-23517 was published on January 21, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-23517 — fleet

Fix: fleetdm/fleet@5c030e3

CVE-2026-23517 is a CWE-862 vulnerability in github.com/fleetdm/fleet. A fix is available for github.com/fleetdm/fleet — see the affected versions and patch details below.

Fleet has an Access Control vulnerability in debug/pprof endpoints

Also known asGHSA-4r5r-ccr6-q6f6GO-2026-4334

Published

Jan 21, 2026

Updated

Oct 28, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Oct 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-23517.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs22th percentile — riskier than 22% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

5 pkgs affected

🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet/v4

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A broken access control issue in Fleet allowed authenticated users to access debug and profiling endpoints regardless of role. As a result, low-privilege users could view internal server diagnostics and trigger resource-intensive profiling operations.

Impact

Fleet’s debug/pprof endpoints are accessible to any authenticated user regardless of role, including the lowest-privilege “Observer” role. This allows low-privilege users to access sensitive server internals, including runtime profiling data and in-memory application state, and to trigger CPU-intensive profiling operations that could lead to denial of service.

Patches

4.78.3
4.77.1
4.76.2
4.75.2
4.53.3

Workarounds

If an immediate upgrade is not possible, users should put the debug/pprof endpoints behind an IP allowlist.

For more information

If you have any questions or comments about this advisory:

Email us at [email protected] Join #fleet in osquery Slack

Credits

We thank @secfox-ai for responsibly reporting this issue.

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/fleetdm/fleet`	≥ 4.78.0&&< 4.78.3	4.78.3`go get github.com/fleetdm/fleet@v4.78.3`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.77.0&&< 4.77.1	4.77.1`go get github.com/fleetdm/fleet@v4.77.1`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.76.0&&< 4.76.2	4.76.2`go get github.com/fleetdm/fleet@v4.76.2`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.75.0&&< 4.75.2	4.75.2`go get github.com/fleetdm/fleet@v4.75.2`
🐹Go	`github.com/fleetdm/fleet/v4`	all versions	4.78.3-0.20260112221730-5c030e32a3a9`go get github.com/fleetdm/fleet/v4@v4.78.3-0.20260112221730-5c030e32a3a9`

Affected Products

1 product · 5 configurations

Application

fleetfleetdm

≥ 4.78.0 && < 4.78.3

1 version

4.77.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fleetdm/fleet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/fleetdm/fleet to 4.78.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23517 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Summary A broken access control issue in Fleet allowed authenticated users to access debug and profiling endpoints regardless of role. As a result, low-privilege users could view internal server diagnostics and trigger resource-intensive profiling operations. ### Impact Fleet’s debug/pprof endpoints are accessible to any authenticated user regardless of role, including the lowest-privilege “Observer” role. This allows low-privilege users to access sensitive server internals, including runtime profiling data and in-memory application state, and to trigger CPU-intensive profiling operatio