# CVE-2014-6271: GNU Bourne-Again Shell (Bash) Arbitrary Code Execution Vulnerability

- Exploited (CISA KEV): yes, added 2022-01-28
- Published: 2014-09-24
- CVSS: 9.8 CRITICAL (v3.1)
- EPSS: 100.0% (100th percentile)
- CWE: CWE-78

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Before feed history | — | — |
| AWS | Before feed history | — | — |
| Microsoft Azure | Rule published | — | — |
| Google Cloud | Rule published | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2023-08-08 | — |
| Akamai | No public source | — | — |
| OWASP CRS | Before feed history | — | — |

### Microsoft Azure

- undated · listed · rule 932170
  > Rule 932170: Critical - 5 · 1 · Remote Command Execution: Shellshock (CVE-2014-6271)
  Source: https://learn.microsoft.com/en-us/azure/web-application-firewall/afds/waf-front-door-drs
- undated · listed · rule 932171
  > Rule 932171: Critical - 5 · 1 · Remote Command Execution: Shellshock (CVE-2014-6271)
  Source: https://learn.microsoft.com/en-us/azure/web-application-firewall/afds/waf-front-door-drs
- undated · listed · rule 932170
  > Rule 932170: Critical - 5 · 1 · Remote Command Execution: Shellshock (CVE-2014-6271)
  Source: https://learn.microsoft.com/en-us/azure/web-application-firewall/ag/application-gateway-crs-rulegroups-rules
- undated · listed · rule 932171
  > Rule 932171: Critical - 5 · 1 · Remote Command Execution: Shellshock (CVE-2014-6271)
  Source: https://learn.microsoft.com/en-us/azure/web-application-firewall/ag/application-gateway-crs-rulegroups-rules

### Google Cloud

- undated · listed · rule owasp-crs-v042200-id932170-rce
  > Signature owasp-crs-v042200-id932170-rce (sensitivity 1): Remote command execution: shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules
- undated · listed · rule owasp-crs-v042200-id932171-rce
  > Signature owasp-crs-v042200-id932171-rce (sensitivity 1): Remote command execution: shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules
- undated · listed · rule owasp-crs-v030301-id932170-rce
  > Signature owasp-crs-v030301-id932170-rce (sensitivity 1): Shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules
- undated · listed · rule owasp-crs-v030301-id932171-rce
  > Signature owasp-crs-v030301-id932171-rce (sensitivity 1): Shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules
- undated · listed · rule owasp-crs-v030001-id932170-rce
  > Signature owasp-crs-v030001-id932170-rce (sensitivity 1): Shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules
- undated · listed · rule owasp-crs-v030001-id932171-rce
  > Signature owasp-crs-v030001-id932171-rce (sensitivity 1): Shellshock (CVE-2014-6271)
  Source: https://docs.cloud.google.com/armor/docs/waf-rules

### F5

- 2023-08-08 · updated · rule 200003927
  > Updated: signature 200003927 "Bash Shellshock execution attempt (2)" (Command Execution, risk High), systems: Unix/Linux. References: CVE-2014-6271, CVE-2014-7169, CVE-2014-6277, CVE-2014-6278.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2023-09-12 · updated · rule 200003927
  > Updated: signature 200003927 "Bash Shellshock execution attempt (2)" (Command Execution, risk High), systems: Unix/Linux. References: CVE-2014-6271, CVE-2014-7169, CVE-2014-6277, CVE-2014-6278.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2014-6271, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2014-6271, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2014-6271 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2014-6271