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Actively exploited

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

GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute code.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 28 Jan 2022.
  • Rated Critical severity (CVSS 9.8, scored by CISA).
  • It has been in the catalogue for 1,743 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for GNU Bourne-Again Shell (Bash). Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated critical, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 28 Jul 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited GNU Flaws

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CVE-2026-24061GNU InetUtils Argument Injection VulnerabilityAdded 26 Jan 2026CVE-2014-6278GNU Bash OS Command Injection VulnerabilityAdded 2 Oct 2025CVE-2023-4911GNU C Library Buffer Overflow VulnerabilityAdded 21 Nov 2023CVE-2014-7169GNU Bourne-Again Shell (Bash) Arbitrary Code Execution VulnerabilityAdded 28 Jan 2022

All 5 exploited GNU vulnerabilities

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2014-6271
  3. CVE record: CVE-2014-6271
  4. FIRST EPSS
  5. exploit-db.com/exploits/37816/
  6. packetstormsecurity.com/files/128517/VMware-Security-Advisory-2014-0010.html
  7. lists.opensuse.org/opensuse-security-announce/2014-09/msg00034.html
  8. www-01.ibm.com/support/docview.wss?uid=ssg1S1004897
  9. www-01.ibm.com/support/docview.wss?uid=swg21685749
  10. marc.info/?l=bugtraq&m=141577137423233&w=2
  11. marc.info/?l=bugtraq&m=142719845423222&w=2
  12. exploit-db.com/exploits/39918/