Local Privilege Escalation in cloudflared

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.8 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2020-24356: 0.35% estimated exploitation activity in the next 30 days; percentile 28.45 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

In cloudflared versions < 2020.8.1 (corresponding to 0.0.0-20200820025921-9323844ea773 on pkg.go.dev) on Windows, if an administrator has started cloudflared and set it to read configuration files from a certain directory, an unprivileged user can exploit a misconfiguration in order to escalate privileges and execute system-level commands. The misconfiguration was due to the way that cloudflared reads its configuration file. One of the locations that cloudflared reads from (C:\etc\) is not a secure by default directory due to the fact that Windows does not enforce access controls on this directory without further controls applied. A malformed config.yaml file can be written by any user. Upon reading this config, cloudflared would output an error message to a log file defined in the malformed config. The user-controlled log file location could be set to a specific location that Windows will execute when any user logs in.

Published by the source

24 May 2021, 16:56 UTC

Last modified by the source

2 Mar 2023, 21:10 UTC

Source last checked

26 Oct 2026, 14:55 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-hgwp-4vp4-qmm2

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# Patch Next advisory brief: CVE-2020-24356

Advisory: Local Privilege Escalation in cloudflared
IDs: CVE-2020-24356, GHSA-hgwp-4vp4-qmm2
Record: https://patchnext.com/advisories/cve-2020-24356 (revision 1, source checked 26 Oct 2026, 14:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/cloudflare/cloudflared 0.0.0-20200820025921-9323844ea773. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cloudflare/cloudflared: affected < 0.0.0-20200820025921-9323844ea773; fixed in 0.0.0-20200820025921-9323844ea773

## Suggested inspection (read-only)
- Go github.com/cloudflare/cloudflared: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/cloudflare/cloudflared.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-hgwp-4vp4-qmm2 (GitHub-reviewed advisory GHSA-hgwp-4vp4-qmm2 lists affected ranges: Go github.com/cloudflare/cloudflared >=0 <0.0.0-20200820025921-9323844ea773)

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