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BashApplication · Gnu

CVE-2014-6277

HIGH · 10.0 CVSS v2.0 Published 2014-09-27
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
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 bash43-026 does not properly parse function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized memory access, and untrusted-pointer read and write operations) 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. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271 and CVE-2014-7169.

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

A remote code execution vulnerability in GNU Bash (through 4.3 bash43-026) where function definitions embedded in environment variables are improperly parsed during bash startup, allowing attackers to execute arbitrary commands. This variant exists due to incomplete fixes for the original Shellshock vulnerabilities (CVE-2014-6271, CVE-2014-7169), and can also cause denial of service via uninitialized memory access and untrusted pointer operations.

MitigationUpgrade Bash to a version beyond bash43-026 that contains the complete fix, or apply vendor-specific patches. Additionally, restrict or sanitize environment variables passed across privilege boundaries in affected services (OpenSSH ForceCommand, Apache mod_cgi/mod_cgid, DHCP clients).

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
BashApplication
Affected:= 1.14.0= 1.14.1= 1.14.2= 1.14.3= 1.14.4= 1.14.5= 1.14.6= 1.14.7= 2.0= 2.01= 2.01.1= 2.02

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
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

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` and note the version number displayed
    Affected if The version is 1.14.0 through 1.14.7, 2.0, 2.01, 2.01.1, or 2.02, or falls within 1.14.x through 4.3 bash43-026 (the vulnerable range)
  2. Check if Bash parses function definitions from environment variables
    Export a test function definition as an environment variable (e.g., `export TEST_FUNC='() { echo vulnerable; }'`) then execute a new bash shell and observe if the function is defined (run `bash -c 'declare -f TEST_FUNC'`). Alternatively, test by setting an environment variable with a malicious function payload and checking if it executes on bash startup.
    Affected if Environment variables containing function definitions are parsed and the functions become available in child shells, indicating the vulnerability is present
  3. Identify services that pass environment variables to Bash
    Review configuration for services that invoke Bash and accept external input: OpenSSH (ForceCommand, PermitUserEnvironment), HTTP servers with CGI scripts (Apache mod_cgi/mod_cgid), DHCP clients, or any custom application that spawns Bash shells with inherited environment variables.
    Affected if Any service or application passes unsanitized environment variables to Bash processes, creating a potential attack vector for CVE-2014-6277
  4. Test for incomplete Shellshock patches
    Run known Shellshock test commands: `env X='() { :; }; echo VULNERABLE' bash -c 'echo test'` for CVE-2014-6271 and `env X='() { (a)=>\' bash -c 'echo date'` for CVE-2014-7169. If either test produces unexpected output (VULNERABLE printed, or file creation error), patches are incomplete and CVE-2014-6277 may also be present.
    Affected if Any Shellshock test reveals the vulnerability, indicating the patch is incomplete and this CVE likely applies

A system is affected if Bash version is within 1.14.0 to 4.3 bash43-026 AND the system runs services or scripts that pass environment variables to Bash without sanitization.

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 lcamtuf.blogspot.com →
Interim mitigation

Upgrade Bash to a version beyond bash43-026 that contains the complete fix, or apply vendor-specific patches. Additionally, restrict or sanitize environment variables passed across privilege boundaries in affected services (OpenSSH ForceCommand, Apache mod_cgi/mod_cgid, DHCP clients).

Recommended fix High confidence

Bash 4.3 patch level 026 or later, or ideally Bash 5.x (current stable release)

  1. 1. Identify the current Bash version installed on the system by running: `bash --version`
  2. 2. Upgrade Bash to a version that includes the complete fix for Shellshock vulnerabilities (CVE-2014-6271, CVE-2014-6277, CVE-2014-7169)
  3. 3. For RHEL/CentOS systems, run: `yum update bash` or `sudo yum install bash`
  4. 4. For Debian/Ubuntu systems, run: `sudo apt-get update && sudo apt-get install bash`
  5. 5. For Oracle Linux, use the Oracle Linux yum server or ULN with the appropriate security patches
  6. 6. After upgrade, verify the version is 4.3 or later with the patches applied: `env X='() { :;}; echo vulnerable' bash -c "echo this is test"` - should not print 'vulnerable'
  7. 7. Restart any critical services that spawn Bash shells to ensure the updated version is used
Caveat Minimal risk for upgrading from 1.14.x; however, test scripts that rely on Bash-specific behavior as some features may have changed

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

Fix this in Bash Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,380
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,608.

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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-2014-6277 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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