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VulnerabilityAwaiting classification

CVE-2026-47831

HIGH · 7.5 CVSS v3.0 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
No privileges Zero-click 7 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Use of a cryptographically weak random number generator in the GenerateRandomPassword function in bosh-windows-stemcell-builder allows a remote attacker to brute-force the resulting SSH login via TCP/22. Affected versions: bosh-windows-stemcell-builder versions prior to v2019.98.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The GenerateRandomPassword function in bosh-windows-stemcell-builder uses a cryptographically weak random number generator, allowing remote attackers to predict or brute-force SSH passwords on TCP/22 to gain unauthorized access.

MitigationUpgrade bosh-windows-stemcell-builder to v2019.98 or later which implements a cryptographically strong RNG. Additionally, restrict network access to SSH port 22 and implement rate-limiting on authentication attempts as defense-in-depth.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify bosh-windows-stemcell-builder installation
    Search for bosh-windows-stemcell-builder components on your system, or check build logs/history for usage of this tool in your CI/CD pipeline or stemcell build process
    Affected if bosh-windows-stemcell-builder is present in your environment and was used to generate Windows stemcells
  2. Determine installed version of bosh-windows-stemcell-builder
    Check the version of the bosh-windows-stemcell-builder tool by examining its binary, container image tag, or git repository tag if you maintain a local copy
    Affected if The version is below v2019.98 (for example, any version prior to the v2019.98 release)
  3. Verify SSH service is enabled on affected Windows VMs
    Check if the Windows stemcells or VMs built with this tool have SSH (port 22) enabled and accessible. Review network security groups, firewall rules, or stemcell configuration for SSH service settings
    Affected if SSH service on TCP port 22 is enabled and reachable from network locations where untrusted users exist
  4. Confirm weak password generation was used
    Review the stemcell build configuration or generated credentials to determine if the GenerateRandomPassword function was invoked during VM provisioning. Check if passwords were generated client-side by the builder rather than by a secure mechanism on the target system
    Affected if Passwords for SSH access were generated by the bosh-windows-stemcell-builder tool rather than by a cryptographically secure method on the provisioned VM

You are affected if bosh-windows-stemcell-builder versions below v2019.98 were used to build Windows stemcells that have SSH enabled, and the weak RNG was actually used to generate those SSH passwords.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade bosh-windows-stemcell-builder to v2019.98 or later which implements a cryptographically strong RNG. Additionally, restrict network access to SSH port 22 and implement rate-limiting on authentication attempts as defense-in-depth.

Recommended fix Moderate confidence

bosh-windows-stemcell-builder v2019.98 or later

  1. 1. Identify current version of bosh-windows-stemcell-builder in use
  2. 2. Download or access bosh-windows-stemcell-builder version v2019.98 or later from the official Cloud Foundry repository
  3. 3. Replace the existing installation with the updated version
  4. 4. Rebuild any Windows stemcells using the updated builder to ensure new SSH passwords are generated with cryptographically strong randomness
  5. 5. Verify the GenerateRandomPassword function now uses a cryptographically secure random number generator (such as crypto/rand in Go)
  6. 6. Re-deploy any affected stemcells and verify SSH access works with newly generated passwords

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
27.0 hours of engineering $4,800
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-47831 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data