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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 28 Jul 2022.
LinuxOperating system · Oracle

CVE-2014-6271

CRITICAL · 9.8 CVSS v3.1 Published 2014-09-24
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

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
GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka "ShellShock." NOTE: the original fix for this issue was incorrect; CVE-2014-7169 has been assigned to cover the vulnerability that is still present after the incorrect fix.

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

GNU Bash through version 4.3 improperly processes trailing strings after function definitions in environment variable values. When Bash is invoked, it parses these environment variables and executes any commands following the function definition, allowing remote attackers to inject arbitrary code via crafted environment variables.

MitigationUpgrade GNU Bash to a patched version (4.3.25 or later recommended). Audit and restart services that invoke Bash, particularly OpenSSH, Apache with CGI/mod_cgid, and DHCP clients, to ensure the patched Bash is actively used.

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
LinuxOperating system
Affected:= 4= 5= 6
Gluster Storage Server For On PremiseApplication
Affected:= 2.1
VirtualizationApplication
Affected:= 3.4
Enterprise LinuxOperating system
Affected:= 4.0= 5.0= 6.0= 7.0
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0= 7.0
Enterprise Linux EusOperating system
Affected:= 5.9= 6.4= 6.5= 7.3= 7.4= 7.5= 7.6= 7.7
Enterprise Linux For Ibm Z SystemsOperating system
Affected:= 5.9_s390x= 6.4_s390x= 6.5_s390x= 7.3_s390x= 7.4_s390x= 7.5_s390x= 7.6_s390x= 7.7_s390x
Enterprise Linux For Power Big EndianOperating system
Affected:= 5.0_ppc= 5.9_ppc= 6.0_ppc64= 6.4_ppc64= 7.0_ppc64

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

CVSS:3.1/AV:N/AC:L/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. Determine installed Bash version
    Run `bash --version` or `rpm -q bash` to get the exact version number
    Affected if Version is 4.3 or earlier (the vulnerable series)
  2. Identify if Apache with CGI is in use
    Check for mod_cgi/mod_cgid configuration: `httpd -M 2>/dev/null | grep cgi` or inspect Apache config files for 'ScriptAlias' or 'AddHandler cgi-script' directives
    Affected if Apache with CGI modules is enabled and Bash is the default shell for CGI scripts
  3. Check for OpenSSH ForceCommand usage
    Inspect SSH server config: `grep -r ForceCommand /etc/ssh/sshd_config` or look for 'ForceCommand' in active SSH configurations
    Affected if OpenSSH ForceCommand is configured, allowing environment variable injection
  4. Test for vulnerable Bash behavior
    Run this safe probe: `env X='() { :;}; echo VULNERABLE' bash -c "echo test"` - examine the output for the word VULNERABLE appearing
    Affected if The word VULNERABLE prints in the output, confirming the vulnerability exists
  5. Identify CGI-accessible endpoints
    Review web server logs or configs for exposed CGI scripts (.cgi, .pl, .sh under cgi-bin), and check if these scripts invoke Bash
    Affected if CGI scripts that invoke Bash are accessible via web

The system is affected if Bash version is 4.3 or earlier AND Bash is invoked through exposed interfaces like CGI, ForceCommand, or other mechanisms that pass environment variables to Bash.

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
Patch available Apply the vendor patch
Vendor patch bugzilla.redhat.com →
Interim mitigation

Upgrade GNU Bash to a patched version (4.3.25 or later recommended). Audit and restart services that invoke Bash, particularly OpenSSH, Apache with CGI/mod_cgid, and DHCP clients, to ensure the patched Bash is actively used.

Recommended fix High confidence

Bash version 4.3 or later with security patches applied; for RHEL systems, apply the latest bash errata (e.g., bash-4.1.2-33.el6_7.1 or later for RHEL 6)

  1. 1. Identify the current Bash version by running: bash --version
  2. 2. For RHEL-based systems (Red Hat Enterprise Linux 4/5/6/7), run: yum update bash
  3. 3. For Debian/Ubuntu-based systems, run: apt-get update && apt-get install bash
  4. 4. For other Linux distributions, obtain a patched version of Bash from your distribution's security repository
  5. 5. After updating, verify the vulnerability is patched by running: env X='() { :;}; echo vulnerable' bash -c "echo this is a test"
  6. 6. If the fix is successful, the command should output only "this is a test" and NOT display "vulnerable"
  7. 7. Alternatively, test using the official Red Hat test: env CVE='() { :;}; echo CVE-2014-6271' bash -c :
Caveat Minimal risk; Bash updates generally do not break existing scripts unless they rely on undefined behavior or specific version-dependent quirks. Test in staging if possible.

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

Fix this in Linux Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2014-6271 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data