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Rhn Client ToolsApplication · Redhat

CVE-2015-1777

MEDIUM · 5.9 CVSS v3.0 Published 2018-04-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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
rhnreg_ks in Red Hat Network Client Tools (aka rhn-client-tools) on Red Hat Gluster Storage 2.1 and Enterprise Linux (RHEL) 5, 6, and 7 does not properly validate hostnames in X.509 certificates from SSL servers, which allows remote attackers to prevent system registration via a man-in-the-middle attack.

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 rhnreg_ks tool in Red Hat Network Client Tools fails to properly validate the hostname in X.509 certificates from SSL servers during the registration process. This allows an attacker positioned between the client and server (MITM) to present a fraudulent certificate with an invalid hostname, causing the system registration to fail. The vulnerability stems from missing or inadequate hostname verification in the SSL certificate validation chain.

MitigationApply the relevant Red Hat security updates for rhn-client-tools to ensure proper X.509 certificate hostname validation is implemented. Until patched, avoid registering new systems on untrusted networks or verify the certificate chain manually.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Rhn Client ToolsApplication
Affected:all versions

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
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

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. Check if rhnreg_ks is installed
    Run 'which rhnreg_ks' or 'rpm -q rhn-client-tools' to see if the Red Hat Network client tools package containing rhnreg_ks is present on the system
    Affected if The package is installed - the vulnerability exists in all versions of rhn-client-tools
  2. Identify the installed version of rhn-client-tools
    Run 'rpm -qa | grep rhn-client-tools' or 'rpm -q --info rhn-client-tools' to retrieve the exact package version installed
    Affected if Any version is installed - the advisory states all versions are affected
  3. Verify hostname verification behavior during registration
    Attempt a test registration or inspect the SSL verification logic in the rhnreg_ks tool (check /usr/bin/rhnreg_ks or related Python modules for SSL hostname validation calls)
    Affected if The code does not perform proper hostname validation on the X.509 certificate (missing ssl.match_hostname or equivalent check)
  4. Check for SSL certificate validation in network connections
    Run 'strings /usr/bin/rhnreg_ks | grep -i verify' or examine the tool's SSL handling code to see if certificate hostname verification is implemented
    Affected if No hostname verification is found in the SSL validation routine

If rhn-client-tools containing rhnreg_ks is installed on the system, the vulnerability is present because all versions of this package are affected by the missing X.509 hostname validation flaw.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant Red Hat security updates for rhn-client-tools to ensure proper X.509 certificate hostname validation is implemented. Until patched, avoid registering new systems on untrusted networks or verify the certificate chain manually.

Fix this in Rhn Client Tools Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2015-1777 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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