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System Config FirewallApplication · Redhat

CVE-2011-2520

HIGH · 7.8 CVSS v3.1 Published 2011-07-21
Fix available
A fix is available. Upgrade to after 1.2.29 or later.
See remediation →
80/100
Remediation priority · High
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
fw_dbus.py in system-config-firewall 1.2.29 and earlier uses the pickle Python module unsafely during D-Bus communication between the GUI and the backend, which might allow local users to gain privileges via a crafted serialized object.

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

This vulnerability exists in fw_dbus.py, the D-Bus communication module between the system-config-firewall GUI and backend. The application uses Python's pickle module insecurely for serializing/deserializing objects during inter-process communication. Because pickle can execute arbitrary code during deserialization when unpickling untrusted data, a local attacker could craft a malicious serialized object that, when processed by the backend, executes code with the privileges of the firewall configuration tool.

MitigationReplace pickle serialization with a safe alternative such as JSON, or implement cryptographic signing of serialized objects if pickle must be retained. Restrict D-Bus permissions to prevent untrusted processes from sending messages to the firewall configuration service.

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
System Config FirewallApplication
Affected:<= 1.2.29
FedoraOperating system
Affected:= 15

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/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. Check if system-config-firewall is installed
    Run 'rpm -q system-config-firewall' (RHEL/CentOS) or check package manager for the firewall configuration tool
    Affected if Package is not installed or version cannot be determined from package query
  2. Determine the installed version
    Run 'rpm -q --info system-config-firewall' or 'system-config-firewall --version' if available, then compare to affected range ( <= 1.2.29 for Red Hat, = 15 for Fedora)
    Affected if Version number matches or falls within the affected ranges (1.2.29 or lower for Red Hat, or Fedora 15)
  3. Locate the fw_dbus.py module
    Search for fw_dbus.py in common Python paths: 'find /usr -name fw_dbus.py 2>/dev/null' or check the system-config-firewall package files with 'rpm -ql system-config-firewall'
    Affected if File is found and belongs to the affected package
  4. Verify pickle usage in the module
    If fw_dbus.py is found, inspect its contents: grep -i 'pickle' /path/to/fw_dbus.py
    Affected if The file contains pickle import and uses pickle.load(), pickle.loads(), pickle.dump(), or pickle.dumps() for serialization/deserialization
  5. Check D-Bus service configuration
    Examine D-Bus service definition for system-config-firewall in /etc/dbus-1/system.d/ or via 'dbus-send --system --dest=org.fedoraproject.FwConfigZone /org/fedoraproject/FwConfigZone org.freedesktop.DBus.Introspectable.Introspect'
    Affected if D-Bus service is exposed and accepts messages from untrusted processes

A system is affected if system-config-firewall (or its Fedora equivalent) is installed at version 1.2.29 or lower (or Fedora 15) and the fw_dbus.py module uses pickle for serializing/deserializing D-Bus communication objects.

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
Upgrade available Upgrade to a release after 1.2.29
Interim mitigation

Replace pickle serialization with a safe alternative such as JSON, or implement cryptographic signing of serialized objects if pickle must be retained. Restrict D-Bus permissions to prevent untrusted processes from sending messages to the firewall configuration service.

Fix this in System Config Firewall Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2011-2520 in production — separate from our analysis above.

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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
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  • No spam, self-promotion, credentials, or personal data