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High, CVSS 7.5amended

FaucetSDN Ryu Denial of Service Vulnerability

CVE-2020-35139GHSA-4987-5p3p-9r27

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI ryu

    Affected
    <= 4.34
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2020-35139: 0.95% estimated exploitation activity in the next 30 days; percentile 61.42 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

An issue was discovered in OFPBundleCtrlMsg in parser.py in FaucetSDN Ryu version 4.34, allows remote attackers to cause a denial of service (DoS) (infinite loop).

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-4987-5p3p-9r27

  2. Revision 1 · created ·

    Published from osv record GHSA-4987-5p3p-9r27

Agent brief

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# Patch Next advisory brief: CVE-2020-35139

Advisory: FaucetSDN Ryu Denial of Service Vulnerability
IDs: CVE-2020-35139, GHSA-4987-5p3p-9r27
Record: https://patchnext.com/advisories/cve-2020-35139 (revision 2, source checked 26 Oct 2026, 13:12 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI ryu: affected <= 4.34

## Suggested inspection (read-only)
- `python -m pip show ryu`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ryu.
- 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://osv.dev/vulnerability/GHSA-4987-5p3p-9r27 (OSV record GHSA-4987-5p3p-9r27 lists affected ranges: PyPI ryu >=0 <=4.34)
- Verified: https://github.com/advisories/GHSA-4987-5p3p-9r27 (GitHub-reviewed advisory GHSA-4987-5p3p-9r27 lists affected ranges: PyPI ryu >=0 <=4.34)

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