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Critical, CVSS 9.3amended

Code injection in ymlref

CVE-2018-20133GHSA-8r8j-xvfj-36f9

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 ymlref

    Affected
    <= 0.1.1
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
9.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2018-20133: 1.83% estimated exploitation activity in the next 30 days; percentile 78.93 (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.

ymlref is a library that allows to load Yaml documents and resolve JSON-pointer references inside them. ymlref versions up to 0.1.1 allow code injection.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-8r8j-xvfj-36f9

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-8r8j-xvfj-36f9

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2018-20133

Advisory: Code injection in ymlref
IDs: CVE-2018-20133, GHSA-8r8j-xvfj-36f9
Record: https://patchnext.com/advisories/cve-2018-20133 (revision 3, source checked 26 Oct 2026, 13:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
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 ymlref: affected <= 0.1.1

## Suggested inspection (read-only)
- `python -m pip show ymlref`: 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 ymlref.
- 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-8r8j-xvfj-36f9 (OSV record GHSA-8r8j-xvfj-36f9 lists affected ranges: PyPI ymlref >=0 <=0.1.1)
- Verified: https://github.com/advisories/GHSA-8r8j-xvfj-36f9 (GitHub-reviewed advisory GHSA-8r8j-xvfj-36f9 lists affected ranges: PyPI ymlref >=0 <=0.1.1)

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